- The average September temperature of 66.4°F was 1.0°F above the 20th Century average and ranked as the 32nd warmest based on preliminary data.
- On a regional level, the West experienced its warmest September on record. The Northwest and West North Central experienced their sixth and eleventh warmest such periods.
- Nevada experienced its warmest September of the 115-year record. California's average temperature tied with 1984 as the warmest on record. In addition, six other states observed September temperatures among their ten warmest: Montana (3rd warmest), North Dakota (3rd), Idaho (4th), Utah (5th), Minnesota (6th), and Oregon (8th).
- In the South, a combination a slow-moving storm system during the beginning of the month and two surface cold fronts during the last week resulted in much below normal temperature averages in Kansas (10th coolest) and Oklahoma (11thcoolest).
- Several divisions in the northern tier states along the Canadian border as well Nevada and Montana averaged record high temperatures during the month. In North Dakota, three contiguous divisions were record warmest in September (Division 1, 2, and 3). Divisions 1 and 2 in Minnesota also experienced record warm temperature averages. Other record warm divisions were in Nevada (Division 1 and 3) and Montana (Division 2).
- For the year-to-date (January–September) period, the contiguous U.S. ranked 29thwarmest. New Mexico and Arizona recorded their tenth- and eleventh-warmest such periods on record, respectively.
- Precipitation was exactly the long-term average for the contiguous U.S. as a whole, but regional amounts varied widely. The South experienced its sixth-wettest September, which was countered by the sixth-driest such period in the East North Central region.
- An upper level storm system stalled over the Deep South during the month, bringing copious rains to the region. Statewide-averaged rainfall was among the ten wettest for four southern states (Arkansas, 2nd wettest; Tennessee (5th), Mississippi (6th), and Alabama (6th)).
- Despite record and flood-producing rains in northern Georgia, drier conditions near the coast kept the state's overall average out of the top ten wettest. However, several divisions in the Southeast averaged a record amount of precipitation averages for the month. In Georgia, Division 1 averaged 11.39 inches, breaking the old record of 9.56 inches set back in 1957. Division 2 averaged 13.07 inches, surpassing the previous record of 12.57 inches recorded just five years prior. In Alabama, Division 3 averaged 10.91 inches of precipitation, breaking the previous record of 10.62 inches set in 1906.
- Maine and Wisconsin each experienced their fourth driest September and both New Hampshire and Michigan had their seventh driest such periods.
- Persistent wetness in Arkansas resulted in the state's 10th wettest year-to-date period, while the lack of monsoon moisture this summer helped hold Arizona to its fifth driest year-to-date period in 115-years of records.
- By the end of September, moderate-to-exceptional drought covered 15 percent of the contiguous United States, based on the U.S. Drought Monitor. Drought intensified in the Upper Midwest and eastern Carolinas, while remaining entrenched in much of the West. Drought conditions remained severe in south Texas, despite some improvement.
- About 27 percent of the contiguous United States had moderately-to-extremely wet conditions at the end of September, according to the Palmer Index (a well-known index that measures both drought intensity and wet spell intensity). Additional drought information can be found on the State of the Climate - Drought page.
Other Items of Note
- Severe weather was limited in September. In the contiguous U.S.; only 10 preliminary tornado reports were recorded by the Storm Prediction Center. Even if all September reports are confirmed, it will represent only 8 percent of the three-year average of 82. With the exception of June, U.S. tornadic activity was well below average to date during 2009.
- During mid-month, a persistent low pressure system in the Deep South and a high pressure system off the eastern seaboard channeled heavy rains into the western Carolinas and the northern half of Georgia. The rains and already-saturated grounds combined to create runoff that overwhelmed many streams and rivers. Major to record flooding occurred across the Atlanta metropolitan area. Eight-day precipitation totals as high as 24 inches were reported in the region.
- During September, 5,535 fires burned approximately 378,523 acres, each of which was below the 2000–2009 average for the month. The acreage lost to wildfire was roughly half of the 2000–2009 average. For the year to date (January–September), 70,217 fires was slightly above the 10-year average, while acreage burned was slightly less than average.
These regional summaries were provided by the six Regional Climate Centers and reflect conditions in their respective regions. These six regions differ spatially from the nine climatic regions of the National Centers for Environmental Information.
Northeast Region (Information provided by the Northeast Regional Climate Center)
- The Northeast had its third warmest September since 1895. The average temperature was 65.3 degrees F (18.5 degrees C), 4.6 degrees F (2.6 degrees C) above normal. Delaware, Maryland, and West Virginia had a record warm September. Pennsylvania had its second warmest September since recordkeeping began, while Massachusetts, New Jersey, New York, Rhode Island, and Vermont had their third warmest. Connecticut and New Hampshire recorded their fourth warmest September on record, while Maine ranked this September as its 12th warmest. Temperature departures ranged from 2.4 degrees F (1.3 degrees C) above normal in Maine to 6.2 degrees F (3.4 degrees C) above normal in West Virginia. Elkins, West Virginia, and Atlantic City, New Jersey, had their warmest September on record, while Erie, Pennsylvania, had its greatest number of September days with a high of at least 90 degrees F (32 degrees C).
- September 2018 was the fourth wettest September on record for the Northeast. The region received 6.48 inches (164.59 mm) of rainfall, 165 percent of normal. West Virginia had a record wet September, and eight additional states ranked this September among their twenty wettest on record: Pennsylvania, third wettest; Maryland and Rhode Island, fourth wettest; Connecticut and New Jersey, sixth wettest; Massachusetts, eighth wettest; Delaware, 11th wettest; and New York, 20th wettest. Vermont and Maine were the only two drier-than-normal states. Precipitation for all states ranged from 79 percent of normal in Maine to 271 percent of normal in West Virginia. Five major climate sites had a record wet September: Huntington, Charleston, and Beckley in West Virginia; Atlantic City, New Jersey; and Bridgeport, Connecticut.
- The U.S. Drought Monitor released on September 6 showed 8% of the Northeast in a severe or moderate drought and 13% of the region as abnormally dry. These areas included northern and western New York, much of Vermont, parts of New Hampshire, portions of Maine, southeastern Massachusetts, and southern Rhode Island. Much-needed rain during the month improved conditions slightly in many of these areas, with the exceptions being eastern Maine and east of Lake Ontario in New York as abnormal dryness expanded. The U.S. Drought Monitor released on September 27 showed 5% of the Northeast in a severe or moderate drought and 16% of the region as abnormally dry. The dry conditions led to small fruit and a large loss of blueberries in parts of Vermont. In addition, farmers in parts of that state were weeks behind in planting fall cover crops. Farmers in northern New York reported decreased hay and pasture production. In Aroostook County, Maine, dry conditions contributed to a hay shortage, with some farmers likely having to use supplemental feed for their animals this winter. The dry conditions also allowed bedstraw, an invasive plant species, to flourish, reducing the number of acres of hay for some farmers. Growers in Maine also reported smaller sized apples. Springs and private wells continued to run dry in parts of northern Vermont. The town of Franklin trucked in water to replenish its water system, which is spring-fed. Residents were asked to conserve and boil water. The village of Waterville also asked residents to conserve water. Stowe's water system was okay, but one of the two primary wells was around ten feet lower this year (mid-September) compared to last year. Water levels at two dams on the Lamoille River were too low to make electricity. Companies that drill, deepen, or replenish wells have seen increased business.
- Up to 9.50 inches (241.30 mm) of rain fell from September 8 to 10 in western and southern parts of the Northeast. This resulted in flooding, which led to numerous closed roads, some flooded basements, and several water rescues. From September 17 to 18, the remnants of Florence brought more heavy rain to the region. Rain totals were generally up to 6 inches (152 mm). The rain led to flooded roads, bridges, and homes, as well as water rescues and some evacuations. Thunderstorms produced wind gusts of up to 70 mph (31 m/s) that caused mostly tree damage on September 6 in eastern Maine and on September 21 in western New York.
- For more information, please visit the Northeast Regional Climate Center Home Page.
Midwest Region (Information provided by the Midwest Regional Climate Center)
- September precipitation across the Midwest ranked as the 11th wettest in history (beginning 1895) with 149 percent of normal. Seven states had statewide values above normal while only Michigan (93 percent of normal) and Missouri (86 percent) were drier than normal. Ohio ranked as the second wettest in its history with 198 percent of normal. Iowa (235 percent) and Kentucky (241 percent) both ranked as the third wettest in their respective histories. Two large areas in the Midwest had between 150 and 400 percent of normal, one included all of Iowa, northwestern Illinois, southwestern Wisconsin, and southern Minnesota while the other covered much of the Ohio River valley including most of Kentucky, southern Illinois and Indiana, and the southern two-thirds of Ohio. Over half of the stations in each of the Midwest's nine states recorded at least one day in September with 1.00 inches (25 mm) or more of precipitation. Daily precipitation records were set nearly 700 times in September, with dozens in each Midwest state, and at least one record set on 25 of 30 days in September including at least a dozen records on 17 of those days.
- September temperatures in the Midwest ranked as the 11th warmest in history (since 1895) averaging 3.7 degrees F (2.1 C) above normal. Ohio set a new record for the warmest September and four statewide values (Illinois 9th, Indiana 6th, Kentucky 7th, Michigan 9th) ranked among the 10 warmest. The remaining four Midwest states were in the warmest 20 percent of their histories as well with all averaging at least 2.1 degrees F (1.2 C) above normal. Temperatures reached 100 degrees F (38 C) in Minnesota, Missouri, and Indiana and at least 93 degrees F (34 C) in all nine Midwest states. Daily temperature records numbered more than 1000 on the record high end of the scale compared to just over 300 on the record low side. Nearly all of the record low temperatures were record low maximum temperatures, many occurring from the 8th to the 11th or the 29th to 30th. The record highs were mostly recorded as record high minimum temperatures in the first week of September and a mix of record high maximums and minimums from the 14th to the 21st.
- Drought eased slightly in September. As of the August 28th US Drought Monitor, just over 16 percent of the Midwest was in drought, 7 percent in severe drought, 2 percent in extreme drought, and a half percent in exceptional drought. Those coverages dropped, particularly in the first half of the month, to 8.5 percent, 1.7 percent, 0.4 percent, and 0.01 percent respectively as of the September 25th Drought Monitor.
- Severe weather was reported on 19 days in September across the Midwest. Minnesota had more than 100 reports while Missouri had just a couple reports during the month. Tornadoes were reported on 7 days in September with at least one report in every state except Missouri. Large hail was reported a few dozen times with most occurring in Iowa and Minnesota. Flooding was a recurring problem in Iowa, Minnesota, and Wisconsin both during the first week of September and again during the third week of September.
- The first freeze of the season came to the northwestern part of the region in late September which is near the median date for first freeze in that area. The freeze brought an end to the growing season. Corn harvest in the Midwest was ahead of schedule across the region as September came to a close, however some areas were unable to get into their fields due to wet conditions. Soybeans were rated mature at rates ahead of average as well in all nine Midwest states.
- For further details on the weather and climate events in the Midwest, see the weekly and monthly reports at the Midwest Climate Watch page.
Southeast Region (Information provided by the Southeast Regional Climate Center)
- Temperatures were much warmer than normal across most of the Southeast in September. Temperature departures ranged from slightly cooler than normal in a small portion of the Florida Everglades to more than 8 degrees F (4.4 degrees C) warmer than normal in western Virginia and North Carolina. Puerto Rico reported temperatures near normal across the island this month. Many mainland stations reported one of their warmest Septembers on record, including Shelby, NC (1936-2018; 1st warmest), Asheville, NC (1892-2018; 1st warmest), Tarpon Springs, FL (1894-2018; 1st warmest), Gainesville, FL (1890-2018; 1st warmest), and Atlanta, GA (1878-2018
- 2nd warmest). Tampa, FL (1890-2018) reported a monthly average temperature of 85.9 degrees F (29.9 degrees C), which broke the old monthly temperature record for any month previously held by June 1998 with a temperature of 85.6 degrees F (29.8 degrees C). Norfolk, VA (1873-2018; 1st warmest) reported 79.1 degrees F (26.2 degrees C), which was 6.8 degrees F (3.8 degrees C) warmer than normal. Key West, FL (1874-2018; 1st warmest), which is in an area with little year-to-year variability because of the surrounding ocean, observed 85.8 degrees F (29.9 degrees C), 2.6 degrees F (1.4 degrees C) warmer than normal. Greenville, SC (1954-2018; 1st warmest) reported 79.9 degrees F (26.6 degrees C), which was 8.4 degrees F (4.7 degrees C) warmer than normal and the highest temperature departure observed in the region in September. Seven stations reported a temperature of 100 degrees F (37.8 degrees C) during the month, including Monroe, NC and Columbia, SC (on the 6th), Macon, GA and Andalusia, AL (on the 18th) and Eufaula, Muscle Shoals and Childersburg, AL (on the 20th). The 100 degree F (37.8 degree C) reading in Macon, GA was the first September 100 degree F reading since September 8, 1990; in Muscle Shoals, AL it was the first September 100 degree reading since September 2, 2011. The coolest maximum temperatures in Florida and Alabama were on September 2 and 3 due to the clouds and rain associated with Tropical Storm Gordon. In North Carolina and Virginia, the lowest maximum temperatures occurred on September 23 in the cloudy and rainy conditions north of a stationary front draped across North Carolina and Tennessee. Appomattox, VA (1956-2018; 3rd coldest) reported a high of 63 degrees F (17.2 degrees C) on that date. While maximum temperatures were above normal at most locations, the biggest contribution to the warmth was from high minimum temperatures, which set records across the region. Over 120 long-term stations (at least 50 years of record), including 44 stations with over 100 years of record, had their highest September average minimum temperature ever. Almost every station in Alabama, Florida, Georgia, South Carolina and eastern North Carolina did not experience a single morning with a temperature at or below 60 degrees F (15.6 degrees C) during September. Several stations, including Brunswick, GA (73 degrees F or 22.8 degrees C; 3rd warmest minimum for the month), reported that temperatures never got below 70 degrees F (21.1 degrees C). A number of inland airport stations reported new records for the number of hours with a dew point temperature of 65 degrees F (18.3 degrees C) or higher, including Charlotte, NC, Greenville-Spartanburg, SC and Asheville, NC, which reported more than 500 additional hours of very humid conditions above their previous records. The high humidity associated with these elevated dew points was one of the contributing factors to the record-setting high minimum temperatures across the region.
- Precipitation across the Southeast in September was highly variable. This was due to the presence of a dominating high pressure system that suppressed convective showers in the central part of the region and two tropical systems that brought record-breaking rainfall along the paths of the storms. Drier than normal conditions were observed in most of Georgia and the Florida Panhandle, with the driest areas found along the East Coast, especially in northeast Florida and the South Carolina coast south of Charleston. Monthly precipitation totals in the areas not affected by the tropical storms ranged from 70 to less than 25 percent of normal. The Melbourne, FL airport (1942-2018; 1st driest) received only 1.40 inches (36 mm) for the month, 6.24 inches (159 mm) drier than normal. Daytona Beach, FL (1923-2018; 2nd driest) received 1.44 inches (37 mm) of rain, 5.54 inches (140 mm) drier than normal. Albany, GA (1947-2018; 1st driest) received only 0.50 inches (13 mm) during the month. Drier than normal conditions were also observed across all of Puerto Rico and the US Virgin Islands, with amounts ranging from 1.7 to 6.1 inches (43 mm to 155 mm) drier than normal across the islands. Those dry conditions led to the expansion of drought across that area. In contrast to the dry areas in the central part of the Southeast, areas along the tracks of the tropical systems received very heavy rainfall. Late on September 4, Tropical Storm Gordon moved inland along the Florida Panhandle, bringing heavy rain to Pensacola, FL and northwest into much of Alabama and ending the drought which had been occurring in that region. Pensacola, FL (1879-2018; 3rd wettest) received 18.25 inches (464 mm) of rain for the month, 12.27 inches (312 mm) wetter than normal; of that, 6.40 inches (163 mm) fell on September 5 alone as a feeder band from T. S. Gordon brought hours of rain to the station. The rainfall total from Gordon in Pensacola was 12.73 inches (323 mm). In Alabama, the highest rainfall from Gordon was 8.53 inches (217 mm) north of Bay Minette in the southeast part of the state. Later in the month, Hurricane Florence made landfall near Wrightsville Beach, NC on September 14 as a Category 1 storm. Florence moved very slowly westward over the region for a period of three days and continued to drop very heavy rain, before mid-latitude steering currents finally turned the system to the north. The highest rainfall amount from Florence in North Carolina, 35.93 inches (913 mm) northwest of Elizabethtown and 23.63 inches (600 mm) west of Loris in South Carolina, are likely to become new record hurricane rainfalls for those two states. Most of southeastern North Carolina and parts of northeastern South Carolina received rain in excess of a 1000-year return period. Wilmington, NC (1871-2018; wettest month and September on record) received 24.13 inches (621 mm) for the entire month, 16.29 inches (414 mm) wetter than normal, largely due to rain from Florence. Farther inland, Mount Mitchell, NC (1980-2018; 3rd wettest) received 20.70 inches (526 mm) for the month, 13.24 inches (336 mm) wetter than normal; of that 11.14 inches (283 mm) was from Florence. Rocky Mount, VA (1905-2018) reported 14.90 inches (378 mm) for the month, 10.31 inches (262 mm) wetter than normal. Extreme rainfall in the region over several days led to many new record crests for rivers in the area, leading to the displacement of thousands of residents and hundreds of water rescues. At the end of September, the Waccamaw River near Conway, SC had just dropped below the previous record flood level from Hurricane Matthew in 2016 and was expected to continue as a major flood until October 8. The largest storm surges reported from Florence were in New Bern and Emerald Isle, NC, where water levels reached 10.1 feet and 7.0 feet (3.1 m and 2.1 m) above ground, respectively. Wilmington, NC (1935-2018) reported a new high water level (storm tide) of 3.60 feet (1.10 m) above the high tide mark, surpassing the old record of 3.48 feet (1.06 m) set on October 8, 2016 during Hurricane Matthew. Fifty deaths have been confirmed from the storm as of the end of September; many of the early deaths from the storm were due to vehicles driven through flooded roadways. There were 167 severe weather reports across the Southeast during September, which is 167 percent of the median monthly frequency of 100 reports during 2000-2016. At least one severe weather report was recorded on 19 days during the month, but the majority of reports were made during the passages of Tropical Storm Gordon through western Florida and southern Alabama on September 1 through 4 and Hurricane Florence in North Carolina and Virginia on September 13 through 16. There were five hail reports during the month, three in North Carolina and one each in Florida and Virginia. A total of 37 tornado reports were issued during the month, nearly 3.4 times the median frequency of 11 tornadoes observed from 2000 to 2016. Strong winds (125 reports) comprised 75 percent of all severe weather reports. The strongest winds from Tropical Storm Gordon were reported at Dauphin Island, AL (74 mph; 33 m/s), Mobile, AL (57 mph; 25 m/s), and Pensacola, FL (52 mph; 23 m/s) on September 4, as the center of circulation approached the coast. One confirmed tornado was reported from T. S. Gordon in Santa Rosa County, FL on September 4. Strong winds and tornadoes associated with Hurricane Florence were observed in coastal North Carolina on September 13, as the eye of Florence moved slowly through the region, and tornadoes were observed through September 17 as the remains of Florence turned northward. In all, there were 28 confirmed reports of tornadoes from Florence, including one EF-2 tornado in Chesterfield County, VA, eleven EF-1 tornadoes, and 16 EF-0 tornadoes. The Virginia tornado caused the second death from Florence in the state, an employee of a flooring company located where the tornado touched down just south of Richmond. In North Carolina, Wilmington reported a wind gust of 105 mph (47 m/s) and Lumberton reported 69 mph (31 m/s) on September 14. Cape Hatteras reported a wind gust of 67 mph (30 m/s) and New Bern reported a gust of 56 mph (25 m/s) on the 13th. A buoy 30 miles SE of New River Inlet reported a wind gust of 112 mph (50 m/s), as Florence approached shore. In South Carolina, Florence and North Myrtle Beach each reported wind gusts of 59 mph (26 m/s) and Charleston reported a gust of 53 mph (24 m/s) on the 14th. Farther inland, Augusta, GA reported a peak wind gust of 39 mph (17 m/s) and Raleigh-Durham, NC reached a peak wind gust of 47 mph (21 m/s). Hurricane Florence weakened to a Category 1 storm before making landfall, and the most severe impacts of the storm came not from the winds but from the 10-foot storm surge followed by the extreme impacts of more than 30 inches (762 mm) of rain across a large portion of southeastern North Carolina. At one point, more than a dozen river gauges in North Carolina alone had reached major flood stage; portions of I-40 and I-95 were both closed due to the flooding, and traffic was rerouted westward through Chattanooga, TN. In New Bern, NC, storm surge from Florence damaged or destroyed more than 4,300 homes and 300 businesses, resulting in a loss of $100 million in combined residential and commercial damage. The North Carolina Division of Public Safety reported that 5,214 people and 1,067 animals were rescued from the high waters. Rain from the remains of Florence were observed all the way into New England as the storm was absorbed into a frontal system. The total economic impact from the storm was preliminarily estimated at $38-50 billion, and since many areas were still inaccessible, these estimates are likely to rise, as more properties are inspected. After Florence passed, only a few reports of severe weather were reported for the rest of the month. On September 18, Brunswick, GA reported a 58 mph (26 m/s) wind from a thunderstorm. On September 27, strong storms brought scattered high winds and one likely tornado to a region stretching from west central Georgia to north central North Carolina, including a likely tornado in Anderson County, SC.
- Dry conditions in areas of the Southeast that were not affected by tropical storms led to the development of moderate drought in northern Alabama, central Georgia and southern South Carolina during the month. Many agricultural producers noted that crop development came to a virtual standstill due to the dry conditions, with soybeans, cotton, and pecans all suffering from losses in yield due to lack of moisture, stressing the plants. Peanut farmers noted that it was so dry they could not even dig up peanuts to do maturity checks and observed that the ground was so hard that it would be difficult to dig the peanuts when they were ready. Livestock producers were forced to start feeding hay early when pastures dried up and hay production came to a halt due to the lack of forage growth. In Puerto Rico, the area of abnormally dry conditions contracted even though precipitation was less than normal across the island. In areas affected by Tropical Storm Gordon and Hurricane Florence, dry conditions were wiped out by the heavy rain, but damage to agriculture was much more severe than in dry areas. In western Florida, southwest Georgia and southern Alabama, winds and rain from Gordon hit fields just as cotton and peanut harvest was underway. Many cotton plants blew over in the high winds and were not expected to straighten up, resulting in rotted bolls due to contact with the wet ground and difficulty running harvesters through the fields. Estimates of damage to peanuts were awaiting the results of harvest while the peanuts are still in the ground. The winds from Gordon also blew down many pecans in Alabama just before harvest, resulting in significant loss in yield. Heavy winds, storm surge, and extreme floods from heavy rains due to Hurricane Florence caused huge impacts for North and South Carolina as well as lesser impacts in Virginia. In South Carolina, agricultural losses alone were estimated to surpass $125 million, including an estimated loss of 75 percent of the cotton crop ($56 million). Peanuts, soybeans and vegetables were also affected in South Carolina. In North Carolina, estimated losses to agricultural alone top $1.1 billion. Losses to row crops such as corn, soybeans and tobacco were estimated at $987 million, including 50 to 100 percent of unharvested tobacco. Other losses include $70 million to commercial forests, $30 million for lawn and landscaping, $27 million for vegetables and horticultural crops, and $23 million for livestock. The storm killed an estimated 5,500 hogs and 4.1 million chickens and turkeys. The total estimated losses from Florence from Moody's Analytics range from $38 to $50 billion, including the losses to agriculture, infrastructure, buildings and businesses.
- For more information, please visit the Southeast Regional Climate Center Home Page.
High Plains Region (Information provided by the High Plains Regional Climate Center)
- After a cool August, September was warm for most of the High Plains region, especially across Colorado and Wyoming where many locations ranked among the top 10 warmest Septembers on record. On the other hand, precipitation varied across the region, with areas in the eastern High Plains experiencing excessive rainfall and flooding, while western areas of the region continued to be impacted by drought conditions. Streamflows were reflective of conditions, as high flows could be found throughout southeastern South Dakota, eastern Nebraska, and central Kansas, while streamflows were abysmal in Colorado and southern Wyoming.
- September 30th marked the end of the water year, which is defined as the period from October 1 - September 30. Looking at precipitation during the water year is not only helpful to examine in mountainous areas where snowpack and its runoff primarily determine water supply, but also in other areas where the growing season is coming to a close and soil moisture recharge has begun. Water-year precipitation was extremely low in portions of Colorado this year, with several locations ranking in the top 10 driest water years on record. The following locations in Colorado ranked in the top 10 driest water years: Pueblo (2nd driest), Grand Junction (3rd driest), Denver (5th driest), and Alamosa (7th driest). It is also worth noting that Alamosa and Denver had their warmest and 9th warmest water years on record, respectively. The lack of precipitation during the water year caused water supply issues in Colorado, as many reservoirs were very low.
- The harvest season is underway as the growing season is coming to an end. Crops matured early in much of the region this year due to very warm temperatures in the early part of the summer. As of the end of September, the harvest of corn and soybeans was ahead of schedule for most states in the region. However, producers were having trouble getting into the fields to harvest in wetter areas, so drier conditions are needed in order to make progress.
- Temperatures were below normal in the northern High Plains and above normal across the rest of the region in September. Generally, departures ranged from 2.0 degrees F (1.1 degrees C) below normal in portions of North Dakota to 6.0 degrees F (3.3 degrees C) above normal across much of Colorado. The warmth in the western High Plains resulted in several records breaking into the top 10 of warmest Septembers throughout Colorado and Wyoming.
- The first three weeks of the month were particularly warm throughout Colorado, Wyoming, South Dakota, and Nebraska, with several locations experiencing daily departures of 10.0 degrees F (5.6 degrees C) or more. Widespread maximum temperatures exceeding 90.0 degrees F (32.2 degrees C) occurred from approximately the 15th to the 20th. According to the Colorado Climate Center, Fort Collins had more days exceeding 90.0 degrees F (32.2 degrees C) in September than this location had in August. The excessive heat and dryness caused a resurgence of the fire season in western Colorado and western Wyoming.
- Much of North Dakota and Wyoming experienced their first freeze of the fall season in September. For the most part, the first freeze occurred near the typical date a first fall freeze is expected in these areas. However, extreme northwestern North Dakota experienced an early freeze on the 5th and, according to the State Climatologist of North Dakota, there was some frost damage in lowland areas. For most of the region, however, the risk of frost damage is lower this year due to warm conditions in the early part of summer that ultimately led to the early maturation of crops.
- It was a tale of extremes regarding precipitation in September, as some areas were excessively wet while others were extremely dry. The wettest areas included southeastern South Dakota, eastern Nebraska, and central Kansas, where precipitation was 200 percent of normal in some locations. Sioux Falls, South Dakota, Lincoln, Nebraska, and Salina, Kansas broke into the top 10 wettest Septembers on record. Meanwhile, much of the rest of the region was dry, especially across Wyoming and western Colorado where precipitation was less than 25 percent of normal in some areas. This led to several impressive records for dryness. For instance, Grand Junction, Colorado and Rawlins, Wyoming had their driest Septembers on record, reporting only a trace and 0.02 inches (1 mm), respectively.
- Wet areas across the High Plains experienced several impacts. For instance, heavy rainfall on the 2nd and 3rd caused flash flooding on Wildcat Creek in Manhattan, Kansas. Several CoCoRaHS observations from the area indicated that more than 7.00 inches (178 mm) of rain fell during the two days. Hundreds of people were evacuated and many were left without power. Also, wet fields slowed harvest and producers were concerned about compaction issues. Some crop diseases were reported in Nebraska, such as stalk rot in corn and stem rot in soybeans. Nebraska Extension reported that mosquito numbers were up in eastern Nebraska, and several West Nile Virus cases have been reported as well.
- September was rather quiet in terms of severe weather occurrences in the region. However, it is worth noting that on the 1st, severe thunderstorms with damaging winds moved through Lincoln, Nebraska just after kickoff of the Nebraska Cornhuskers' first football game of the season. Ultimately, the inclement weather led to the game being cancelled, which was the first time in the school's history that a football game was cancelled due to weather.
- Unfortunately, some areas in drought across the region saw the continuation of dry conditions in September. For instance, western Colorado, southern Wyoming, portions of the Dakotas, and northeastern Kansas did not receive any drought relief. Although the primary growing season is coming to an end, winter wheat planting is underway. However, winter wheat producers in these areas were concerned about continued dryness, as moisture is needed going into winter for adequate growth of the crop.
- Both above-normal and below-normal streamflow were observed throughout the High Plains in September. Streamflows were running much above normal in portions of South Dakota, Nebraska, and Kansas. These areas received at least 150 percent of normal precipitation during September. The U.S. Army Corps of Engineers maintained higher-than-average releases from all Missouri River Mainstem projects in September to prepare for the 2019 Missouri River runoff season. The Corps reduced outflows from Gavins Point Dam as a result of heavy rains in southeastern South Dakota. In western Colorado, streamflows continued to be well below normal, as precipitation was less than 25 percent of normal in many locations. September was also dry for much of Wyoming, which caused streamflows to fall below normal throughout portions of the state.
- Drought conditions improved in some areas but worsened in others in September, according to the U.S. Drought Monitor. Overall, the area in drought (D1-D4) in the High Plains increased by approximately three percent. For much of the region it was a dry month, causing drought to intensify.
- Western and northern Colorado experienced warm and dry conditions during September, which exacerbated impacts. For instance, streamflows were low, with many streams experiencing flows that were less than the 10th percentile for this time of year. The drought has impacted water supplies, as reservoir levels continued to drop. Reservoir levels at Lake Powell and Lake Mead, which provide water to multiple states in the West, were less than the 10th percentile in September.
- Drought also intensified in the Dakotas where it has been persistently dry. In North Dakota, producers reported stressed pastures, a shortage of hay, and disappointing soybean yields in dry areas. Producers in the Dakotas have voiced concerns about the dryness coinciding with winter wheat planting.
- Areas that received drought relief in September included northeastern and southwestern portions of Kansas, as well as southeastern Colorado. Heavy rains early in the month brought about a one to two-category improvement in these areas, which helped improve soil moisture conditions.
- For more information, please visit the High Plains Regional Climate Center Home Page.
Southern Region (Information provided by the Southern Regional Climate Center)
- Temperatures for the month of September varied spatially throughout the Southern Region. Parts of southwestern and western Texas experienced temperatures 2 to 4 degrees F (1.11 to 2.22 degrees C) below normal. Most of Louisiana and Arkansas, eastern and northwestern Oklahoma, northern, extreme western, extreme southern, eastern, and parts of central Texas, southern, southwestern, central, and northwestern Mississippi, and western Tennessee experienced temperatures 2 to 4 degrees F (1.11 to 2.22 degrees C) above normal. Parts of northern and northeastern Texas, northwestern, northeastern, and southeastern Oklahoma, northern, northeastern, and southeastern Louisiana, northwestern, northeastern, and southwestern Arkansas, southern, northern, and eastern Mississippi, and central, southern, and northern Tennessee experienced temperatures 4 to 6 degrees F (2.22 to 3.33 degrees C) above normal. Parts of eastern Mississippi as well as southern, northern, and eastern Tennessee experienced temperatures 6 to 8 degrees F (3.33 to 4.44 degrees C) above normal. The statewide monthly average temperatures were as follows: Arkansas—75.10 degrees F (23.94 degrees C), Louisiana—80.30 degrees F (26.83 degrees C), Mississippi—79.10 degrees F (26.17 degrees C), Oklahoma—73.90 degrees F (23.28 degrees C), Tennessee—75.10 degrees F (23.94 degrees C), and Texas—76.30 degrees F (24.61 degrees C). The statewide temperature rankings for September were as follows: Arkansas (twenty-eighth warmest), Louisiana (tenth warmest), Mississippi (seventh warmest), Oklahoma (forty-eighth warmest), Tennessee (sixth warmest), and Texas (fifty-third warmest). All state rankings are based on the period spanning 1895-2018.
- Precipitation values for the month of September were above normal across much of the Southern Region. Parts of northern and extreme western Texas as well as northeastern Oklahoma received 25 percent or less of normal precipitation. Parts of northern, western, and extreme western Texas, northeastern and northwestern Oklahoma, northwestern and southeastern Arkansas, and part of western Mississippi received 50 percent or less of normal precipitation. In contrast, parts of western, southern, central, northern, eastern, and northeastern Texas; western, central, southern, southeastern, and eastern Oklahoma; southern and northern Louisiana, central, southwestern, and northeastern Arkansas, most of Mississippi, and most of Tennessee received 150 percent or more of normal precipitation. Parts of north-central, western, southern, and eastern Texas; northwestern, central, and southern Oklahoma; central and eastern Arkansas; northwestern, northeastern, southwestern, and southeastern Louisiana, central, northwestern, eastern, and parts of northern and southern Mississippi, and western and eastern Tennessee received 200 percent or more of normal precipitation. Parts of northeastern and southern Texas, southern Oklahoma, and east-central Arkansas received 400 percent or more of normal precipitation. An area in southern Texas received 800 percent or more of normal precipitation. The state-wide precipitation totals for the month were as follows: Arkansas—5.21 inches (132.33 mm), Louisiana—7.05 inches (179.07 mm), Mississippi—6.59 inches (167.39 mm), Oklahoma—5.38 inches (136.65 mm), Tennessee—7.20 inches (182.88 mm), and Texas—6.77 inches (171.96 mm). The state precipitation rankings for September were as follows: Arkansas (twenty-third wettest), Louisiana (tenth wettest), Mississippi (tenth wettest), Oklahoma (eighteenth wettest), Tennessee (third wettest), and Texas (first wettest). All state rankings are based on the period spanning 1895-2018.
- At the end of September, exceptional drought conditions were no longer present across the Southern Region. Extreme drought classifications were present in northern and northwestern Texas. Severe drought classifications were present throughout northern, northwestern, extreme western, and east-central Texas as well as southwestern and northeastern Oklahoma. Moderate drought classification was present throughout extreme western, northern, central, southeastern, and eastern Texas, southwestern and northeastern Oklahoma, northwestern, southwestern, and southern Arkansas, northwestern and northern Louisiana, and northeastern Mississippi. There were no drought conditions in Tennessee.
- Across the Southern Region, the total area not experiencing at least abnormally dry conditions increased from just over 40 percent at the end of August to just under 71 percent at the end of September. Over 90 percent of both Arkansas and Tennessee were not experiencing at least abnormally dry conditions, while over 80 percent of Louisiana and Mississippi were not experiencing at least abnormally dry conditions. Texas, at just under 57.5 percent, contained the smallest area lacking at least abnormally dry conditions.
- In September, there were a total of 27 storm reports across Texas, Oklahoma, Arkansas, Louisiana, Tennessee, and Mississippi. There were 5 tornado reports, 2 hail reports, and 20 wind reports. Tennessee tallied the most wind reports (8) and both Tennessee and Mississippi tallied the most tornado reports (2). Both Texas and Louisiana tallied 1 hail report. Tennessee tallied the most reports total (10) while Louisiana and Oklahoma tallied the least (1).
- On September 1, 2018, a wind gust of 63 mph (101.39 kph) was reported near Canyon, Texas.
- On September 2, 2018, a landspout tornado was reported near Lubbock, Texas. Also, a wind gust of 60 mph (96.56 kph) was reported near Camp Houston, Oklahoma.
- On September 5, 2018, a tornado was reported near Kilmichael, Mississippi.
- On September 6, 2018, a tornado was reported near Picayune, Mississippi, damaging several manufactured homes. No injuries were reported.
- On September 20, 2018, there was a report of a car wash roof being blown over onto cars near Conroe, Texas. No injuries were reported.
- On September 24, 2018, a small, short-lived EF-0 tornado was reported near Readyville, Tennessee.
- On September 25, 2018, a small, short-lived EF-1 tornado was reported near Clarkrange, Tennessee, hitting a residence and nearby areas. No injuries were reported.
- For more information, please visit the Southern Regional Climate Center Home Page.
Western Region (Information provided by the Western Region Climate Center)
- Temperatures were well above normal in the Southwest with near to slightly below normal temperatures in the Pacific Northwest and Northern Rockies this month. The end of the Monsoon season brought above normal precipitation to parts of southern Arizona and New Mexico while much of the rest of the West saw below normal precipitation.
- A few storms moved through the Pacific Northwest during the second half of the month bringing cooler than normal temperatures, but the Southwest remained well above normal throughout the entire month. Las Vegas, Nevada, experienced its warmest September on record dating back to 1948 at 88.1 °F (31.2 °C), 5.5 °F (3.1 °C) above normal. Grand Junction, in Western Colorado, saw the second warmest September in 119 years at 71.8 °F (22.1 °C), 5.7 °F (3.2 °C) above normal. Much of coastal California recorded near to below average temperatures for the month. San Francisco averaged 60.4 °F (15.8 °C), 2.3 °F (1.3 °C) below normal. Northeast Montana was also cool this month with an average temperature of 55.2 °F (12.9 °C), 3.8 °F (2.1 °C) below normal.
- September remained dry in Utah punctuating one of the driest water years on record. At Salt Lake City a trace of precipitation was recorded for only the third time since records began in 1928, tying 1943 and 1951 for the driest September on record. Oregon, eastern Washington, and Idaho also saw a well below normal month for precipitation. Moscow, Idaho recorded 0.05 in (1.27 mm), 4% of normal, which ties 1990 and 2012 for the third driest September since records began in 1894. Southeast Arizona and southern New Mexico benefitted from an active September Monsoon. Wilcox, Arizona logged 3.9 in (99.8 mm), 333% of normal, and ranks as the fourth wettest on record since 1898. Most of the monthly total at Wilcox came from two heavy rainfall days with 1.8 in (45 mm) on September 3rd and 1.5 in (38.9 mm) on September 20th. Remnants of Hurricane Rosa provided much needed rain to a small area near the California-Arizona border. On September 30th 0.9 in (22.9 mm) of rain fell at Yuma Proving Ground, Arizona and 0.7 in (17.3 mm) fell at Imperial, California bringing both locations well above normal for the month. According to the United States Drought Monitor conditions degraded to extreme drought in eastern Oregon and severe drought in southern Idaho with small areas of improvement to moderate drought in northeast New Mexico.
- Hawaii was affected by another tropical system this month but impacts were minor compared to the devastating rain from Hurricane Lane last month. This month, Hurricane Olivia became the first tropical system in historical records to make landfall on Maui and Lanai although it was downgraded to a tropical storm by the time it came ashore. Olivia made landfall on the eastern shores of Maui and Lanai on September 12th with sustained winds of 45 mph and brought widespread heavy rainfall. On Maui, Hana received 3.8 in (97.3 mm) over the three-day period from September 11-13 and 7.8 in (198.9 mm) for the month, 115% of normal. O'ahu also saw above normal precipitation over most of the island. Honolulu airport recorded 1.8 in (45.2 mm), 254% of normal and the seventh wettest since records began in 1940. To the north in Alaska a strong upper level ridge was parked over the region for much of the month centered over the western part of the state. This brought widespread above normal temperatures and below normal precipitation. Many locations in southcentral and western Alaska saw record or near record warmth for the month. Anchorage, 55 °F (12.8 °C) and 6.4 °F (3.6 °C) above normal, Bethel, 51.5 °F (10.8 °C) and 5.5 °F (3.2 °C) above normal, and Kotzebue, 49.1 °F (9.5 °C) and 6.8 °F (3.8 °C) above normal, all logged the warmest September on record. In the southeast part of the state Juneau, 2.3 in (57.9 mm) and 26% of normal, Cordova, 3.6 in (92.5 mm) and 27% of normal, and Sitka, 2.4 in (70.0 mm) and 20% of normal, all recorded the driest September on record. Widespread D2 (severe drought) and D1 (moderate) is now present over much of southeast Alaska.
- All Month: Wildfire impacts across the West: A number of large wildfires continue to burn across the west and several new fires ignited in September. In northern California, not far from the devastating Carr fire, the Delta fire started on September 5 and has burned over 60,000 acres (24,281 hectares) and destroyed 20 structures. In northeast Nevada the Range 2 Fire began on September 30th in the Ruby Mountains and has burned over 9,000 acres (3,642 hectares). The Lamoille Canyon area of the Ruby Mountains is a popular tourist destination for camping, hiking, fishing, and other outdoor activities and remains closed until further notice.
- All Month: Widespread drought impacts agriculture in Utah: September was another dry month in one of the driest water years on record for much of Utah and the agricultural communities have seen major impacts. For the first time in ten years an emergency meeting of the Utah Drought Review and Reporting Committee was called to investigate the potential need for an emergency declaration across the state. Many farmers in southern Utah have run out of surface water. Pasture and range conditions are some of the worst in the country with 71% of the grazable land in poor or very poor conditions according to the Climate Prediction Center.
- For more information, please go to the Western Regional Climate Center Home Page.
Citing This Report
NOAA National Centers for Environmental Information, State of the Climate: Monthly National Climate Report for September 2018, published online October 2018, retrieved on August 8, 2022 from https://www.ncei.noaa.gov/access/monitoring/monthly-report/national/201809.