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Climate Extremes Index

The U.S. Climate Extremes Index (CEI) was proposed in 1995 as a framework for quantifying observed changes in climate within the contiguous United States. The CEI is based on a set of climate indicators: extremes in monthly mean maximum and minimum temperatures, heavy 1-day precipitation events, drought severity, the number of days with/without precipitation, and wind intensity of landfalling tropical cyclones.

A CEI value of 0 percent, the lower limit, indicates that no portion of the country was subject to any of the extremes of temperature or precipitation considered in the index. In contrast, a value of 100 percent would mean that the entire country had extreme conditions throughout the time period for each of the indicators, a virtually impossible scenario. Since we're dealing with the upper and lower tenth percentile as a definition of the extremes, and we're looking at the cold and warm (wet and dry) ends of the extremes, the long-term average expected percent area experiencing extremes is 20 percent. Therefore, observed CEI values of more than 20 percent indicate "more extreme" conditions than average, and CEI values less than 20 percent indicate "less extreme" conditions than average.

The CEI is evaluated for eight seasons: spring, summer, autumn, winter, annual, cold season, warm season, and hurricane season. Data and graphics for each season and indicator are updated at the beginning of the month. CEI results indicate that for the annual, summer, warm and hurricane seasons, the percent of the contiguous United States experiencing extreme conditions has been generally increasing since the early 1970s (see figure). Recent percentages are similar to those found during the early 1900s for these same periods.

Visit the Climate Extremes Index for the most current data and graphics and the individual indicators within it.

National Overview:

Like last month, the weather patternweather pattern for July 2010 was dominated by the North Atlantic High over much of the eastern and southern United States. July temperatures averaged warmer than normal along most of the country east of the Mississippi River and across the Southwest. Hundreds of daily maximum temperature records were tied or broken at individual statons, with July 2010 ranking as the warmest July in the 1895–2010 record for Delaware and Rhode Island. The persistence of this pattern over the last several months has resulted in the warmest May-July on record for several east coast states from South Carolina to New Hampshire. The North Atlantic High (also known as the Bermuda High) deflected tropical systems across the Caribbean and Gulf of Mexico this month. Hurricane Alex (which formed in June) dissipated over northern Mexico by July 2nd. A tropical depression which followed Alex in early July brought heavy rainfall and flooding to southern and western Texas. Tropical Storm Bonnie dissipated as it moved into the Gulf of Mexico later in the month. However, moisture from these tropical systems was swept up into the southern Plains and Southeast and contributed to scattered convective and frontal thunderstorms which developed later. The abundant rainfall from tropical systems helped keep July temperatures below normal for Texas.

Due to the mid-latitude location of the continental U.S., the jet stream straddles the boundary between warmer air masses from the lower equatorial latitudes and cooler air masses from the higher polar latitudes. The summer months usually have a quieter polar jet than the winter months, but the jet stream during this July was fairly active. Several cold fronts and surface low pressure systems moving with the jet brought heavy rain and severe weather to parts of the central and northern Plains and adjacent Great Lakes. The rain alleviated drought conditions across parts of the western Great Lakes, but brought flooding to parts of the Midwest and contributed to the failure of the Lake Delhi Dam in Iowa. Some of the fronts penetrated into the Southeast, but weakened under the Bermuda High resulting in only scattered precipitation.

  • Temperature Highlights - July
  • Persistent high pressure systems continued to dominate much of the eastern United States during July, resulting in a nationally averaged temperature that was warmer-than-normal.
  • The intense heat either tied, or shattered, July monthly temperature records in several East Coast cities, including Washington D.C., which recorded an average temperature of 83.1°F (28.4°C). This tied July 1993 for the warmest for any calendar month on record. Other July monthly temperature records were broken, or tied, in Atlantic City, New Jersey and Hartford, Connecticut.
  • It was the hottest July on record for Delaware and Rhode Island. Along the East Coast, each state from Maine to Florida ranked in its top ten warmest. Only Montana, Idaho, and Texas had average temperatures that were below-normal for the month.
  • The Southeast and Northeast climate regions experienced their third and fifth warmest July on record, respectively. Of the nine climate regions within the contiguous U.S., none experienced an average temperature in the below-normal category.
  • May - July and Year-to-Date
  • The May–July period was the warmest on record for the Northeast and Southeast climate regions and was the ninth warmest for the Central region. By contrast, the Northwest had its sixth coolest May-July period.
  • The May–July period produced record warmth for: New Hampshire, Massachusetts, Rhode Island, New Jersey, Delaware, Maryland, Virginia, North Carolina, and South Carolina. Conversely, the same period brought below-average temperatures to: Oregon (fifth coolest), Idaho (seventh), and Montana (eighth).
  • In the Southeast, the below-average temperatures from the winter were still evident in the year-to-date (January–July) period, as Texas, Louisiana, Mississippi, Alabama, Georgia, and Florida were below normal. Meanwhile, Maine, New Hampshire, Vermont, Rhode Island, and Connecticut have experienced a record warm January–July, contributing to a record warm such period for the Northeast climate region.
  • Precipitation Highlights - July
  • Precipitation, when averaged across the country, was much-above-normal, ranking in the top ten percent in the 1895-2010 period. Much of the Plains and Upper Midwest experienced above normal precipitation partly due to moist tropical air which fueled thunderstorms, some of which were severe. These systems stalled out causing major flooding in some areas.
  • Wisconsin had its second wettest July, while Texas had its fourth, Iowa its fifth, and Missouri its eighth. In contrast, it was the tenth driest July for Georgia and Virginia.
  • May - July and Year-to-Date
  • From May through July, persistent rainfall made this period the wettest for Wisconsin, the second wettest for Illinois and Iowa, the third wettest for Michigan and fifth wettest for Washington state.
  • The three-month precipitation average of 17.38 inches in Wisconsin was 5.84 inches above their normal for the month, resulting in their wettest May-July period. The 22.01 inches in Iowa resulted in only its second wettest May–July period, which was 9.40 inches above the long-term-mean. Iowa's record wettest May–July period is 24.43 inches, set in 1993.
  • Precipitation, when averaged across the nation, was much-above-normal, ranking as the tenth wettest May–July period. On the regional level, much of the northern tier United States was above normal. The East North Central region had its second wettest May–July. Both the Central and West North Central region had their ninth wettest and the Northwest had its tenth.
  • Precipitation was well-below normal in Louisiana for the year-to-date period (January–July), as drought conditions continued to deteriorate. The state was more than 9.5 inches below the long-term average for the year, its seventh driest such period in 116 years. Conversely, Iowa was nearly ten inches above average, its third wettest January–July.
  • Other Items of Note
  • On July 23rd, a severe thunderstorm produced a localized swath of very large hail in and near Vivian, South Dakota, including a stone that broke national records for diameter (8.0 inches) and weight (1.93 pounds).
  • On July 25th, an EF-1 tornado touched down in Bronx County, New York, marking only the second ever recorded in the Bronx. On July 26th, an EF-3 tornado hit rural Sheridan County, Montana, killing two. This ties as the deadliest tornado in Montana history, and only the fourth EF-3 or stronger tornado ever observed in the state.
  • Extremes for the most recent year-to-date period (Jan-Jul) were about eight percent above average. Contributing factors include: a large portion of the country with above-normal minimum temperatures, a wet Palmer Drought Serverity Index, extremes in 1-day precipitation and above average number of days with precipitation.
  • The U.S. Drought Monitor reported 8.2 percent of the United States was affected by drought on August 3rd. While slight improvements were seen in the Northern Rockies, Great Lakes area, and eastern Texas, conditions deteriorated around the Mid-Atlantic and Sierra Nevada range.
  • Based on NOAA's Residential Energy Demand Temperature Index (REDTI), the contiguous U.S. temperature-related energy demand was 19.4 percent above average for July. The unusual warmth in the highly populated Northeast and Southeast contributed to the 8th highest July REDTI value in 116 years.
  • Wildfire activity was relatively quiet across the U.S. The number of new fires and the amount of acreage burned were significantly below average. More wildfire information can be found in NCDC's monthly wildfire page.

Alaska Temperature and Precipitation:

Beginning with January 2010 processing, the Alaska temperature and precipitation report is comprised of several datasets at NCDC, integrating GHCN and COOP datasets. Prior to 2010, the Alaskan temperature timeseries was processed with just GHCN data.
  • Alaska had its 20st coldest July since records began in 1918, with a temperature 1.8°F (1.0°C) below the 1971–2000 average.

  • Alaska had its 39th warmest May–July on record, with a temperature that was equal to the 1971–2000 average.

  • Alaska had its 29th warmest year–to–date on record, with a temperature 0.7°F (0.4°C) above the 1971–2000 average.
  • Alaska had its 14th wettest July since records began in 1918, with an anomaly that was 32.0 percent above the 1971–2000 average.

  • Alaska had its 38th wettest May–July on record, with an anomaly that was 2.7 percent above the 1971–2000 average.

  • Alaska had its 24th driest year–to–date on record, with an anomaly that was 6.0 percent below the 1971–2000 average.

For additional details about recent temperatures and precipitation across the U.S., see the Regional Highlights section below. For information on local temperature and precipitation records during the month, please visit NCDC's Records page. For details and graphics on weather events across the U.S. and the globe please visit NCDC's Global Hazards page.

Regional Highlights:

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 Climatic Data Center.

  • Northeast Region: (Information provided by the Northeast Regional Climate Center)
  • July 2010 was the sixth warmest July since 1895 and the seventh consecutive month with above normal readings. The Northeast's average temperature of 72.9 degrees F (22.7 degrees C) was 3.1 degrees F (1.7 degrees C) above normal and 6.2 degrees (3.4 degrees C) warmer than July 2009. It was the warmest July since 1952, which was the warmest July on record with an average temperature of 74.0 degrees F (23.3 degrees C). Ten of the twelve states had a monthly average that fell within the top seven warmest in 116 years; of those, Delaware and Rhode Island had their warmest July on record. Departures ranged from 1.8 degrees F (1.0 degree C) above normal in West Virginia to 4.1 degrees F (2.3 degrees C) above normal in Rhode Island. A heat wave during the first full week of July pushed the mercury into the upper 90's and low 100's (36-39 degrees C) at many locations, breaking records from Caribou, ME to Charleston, WV.
  • Rainfall totals averaged 93 percent of normal in the Northeast. Only two states, Delaware (140 percent), and Pennsylvania (112 percent), had above normal rainfall totals. Of the remaining states in the Northeast, Massachusetts was the driest, with 71 percent of the normal rainfall amount and West Virginia was closest to normal, with a total that was 97 percent of normal. Abnormally dry conditions have expanded into all of the New England states according to the August 3, 2010 U.S. Drought Monitor. In addition, the eastern half of New Jersey, northeastern Pennsylvania, southern Delaware and portions of Maryland and eastern West Virginia were experiencing moderate drought conditions. Severe drought conditions were found in southeastern Maryland, the eastern panhandle of West Virginia and adjoining Washington County, MD.
  • The big weather story this month was the aforementioned heat wave from July 4th to the 9th. With record-breaking temperatures and high humidity, the region's power producers worked hard to keep up with the increased demand for air conditioning. Only scattered outages in Connecticut, Massachusetts, New Jersey and New York were reported. Heat-related illnesses were kept in check with the availability of "cool" rooms, the lack of large-scale power outages and constant hot weather tips from the media and government agencies. There were, however, at least 3 deaths attributed to the excessive heat. Severe storms impacted the region, resulting in wind damage and flash flooding from the 21st to the 25th. In addition, a total of eight tornados, ranging in strength from EF-0 to EF-2 (winds from 65 to 135 mph or 29 to 60 m/s), were confirmed in Connecticut, New York, and Pennsylvania during that time period. Most of the tornados snapped trees, and damaged or destroyed buildings, but at least 7 people were injured from flying glass during the tornado that touched down in the Bronx, NY on the 25th.
  • For more information, please go to the Northeast Regional Climate Center Home Page.
  • Midwest Region: (Information provided by the Midwest Regional Climate Center)
  • July temperatures ranged from near normal in Minnesota, Iowa and parts of Missouri up to 5 degrees F (3 degrees C) above normal to the east and south. Maximum temperatures were within 2 degrees F (1 degrees C) of normal for most of the Midwest but minimum temperatures were warmer. Minimum temperatures were above normal across the region ranging up to 6 degrees F (3 degrees C) above normal in Michigan. Of 575 daily temperature records in July, 485 were record high minimum temperatures.
  • July precipitation was highly variable in the Midwest, but where it rained, it poured. Localized heavy rains fell on many days in various parts of the Midwest. The heavy rains led to flash flooding in many locations in July. Seventy-four Cooperative Stations reported 10 inches (254 mm) or more of rain, 24 stations in Iowa, 19 in Missouri, 16 in Wisconsin, 10 in Illinois, two in Michigan, and one each in Indiana, Kentucky, and Minnesota. Over 300 Midwest stations picked up more than 7 inches (178 mm) of rain. Oelwein, Iowa totaled 20.33 inches (516 mm) for the month, 9.93 inches (252 mm) of that on the night of the 22nd.
  • Two people died from lightning strikes and at least 3 others were struck during the last 10 days of the month. The deaths were in Ft. Knox, Kentucky on the 27th and Pontiac, Illinois on the 28th. Two others were struck in Milwaukee, Wisconsin on the 22nd and one in Duluth, Minnesota on the 27th. All three were taken to local hospitals for treatment.
  • Numerous flash floods caused extensive damage across the Midwest but three events were blamed for four deaths. Two died in Pike County, Kentucky on the 17th, another died in Hannibal, Missouri on the 20th, and the fourth fatality was in Carter County, Kentucky on the 21st. Flash flooding washed away roads, train tracks, and bridges, swamped thousands of acres of farmland, and flooded hundreds of homes.
  • Flooding on the Maquoketa River followed two days of torrential downpours that dropped up to 12 inches (304 mm) of rain across northeast Iowa, southwest Wisconsin, and northeast Illinois. The river swelled to 10 feet (3 m) above flood stage and three feet (1 m) above the previous record stage, flooding more than 4000 acres (1600 hectares) of farmland in Delaware County. Water overtopped the earthen dam, built in the 1920s, that created Lake Delhi. A breach in the dam developed and widened to more than 30 feet (9 m) as the entire 450 acre (180 hectare) lake drained in a day. Two communities downstream, Monticello and Hopkinton, were evacuated.
  • Tornadoes in northern Wisconsin on the 27th included the first confirmed tornado in Iron County since 1970 and the first in Ashland County since 1998.
  • For details on the weather and climate events of the Midwest, see the weekly summaries in the MRCC Midwest Climate Watch page.
  • Southeast Region: (Information provided by the Southeast Regional Climate Center)
  • Continuing the trend that began back in April, mean temperatures in July were above normal across the Southeast region. The greatest departures from normal [more than 4 degrees F (2.2 degrees C) above normal] were found in central Alabama and northern and eastern Virginia, while locations along the immediate coastlines were near normal to slightly above normal. For the second consecutive month, mean monthly temperatures were near normal across Puerto Rico. Over 30 locations in the Southeast experienced their warmest July on record, including Birmingham, AL, Gainesville, FL, Richmond, VA, and Washington, D.C. Numerous other locations came within a degree of tying or breaking their all-time warmest July on record, including Huntsville, AL, Raleigh-Durham, NC, Greenville-Spartanburg, SC, and Tallahassee, FL. Across the region, 589 record daily maximum temperatures were tied or broken in July, and more than half occurred in Virginia and Florida. Norfolk Intl Airport in Virginia tied its all-time daily high temperature of 105 degrees F (40.6 degrees C) on the 24th of the month. According to the Virginia State Climate Office, the Williamsburg-Jamestown Airport came within 1 degree F (0.5 degrees C) of tying the all-time state record when it reached 108 degrees F (42.2 degrees C) on the 7th, 24th, and 25th of the month. Minimum temperatures continued to be exceptionally warm across the Southeast in July, with over 1,200 record daily high minimum temperatures tied or broken during the month. Nearly 100 locations broke or tied their all-time daily high minimum temperature record. On the 25th of the month, Raleigh-Durham Intl Airport in North Carolina registered a minimum temperature of 80 degrees F (26.7 degrees C), which broke the all-time warmest minimum temperature at that location in a record extending back to 1944.
  • Monthly precipitation was generally below normal in July (50-75 percent of normal), though there was much local-scale variability as is typical during the summer in the Southeast. As in June, locations that experienced more thunderstorm activity were near normal or slightly above normal for the month. The wettest locations were found through the central Carolinas and eastern South Carolina, where precipitation for the month ranged from 150 percent to as much as 300 percent of normal. Puerto Rico continued to experience exceptionally wet weather in July, with monthly totals nearly 10 inches (254 mm) above normal along the southern end of the island. Much of this precipitation was tied to the tropical disturbance that would later become Tropical Storm Bonnie. At least one death on the island was attributed to the flooding rains accompanying this storm. Tropical Storm Bonnie produced modest rainfall totals (1-3 inches; 25.4-76.2 mm) across south Florida where it made landfall on the 23rd of the month. The driest locations across the Southeast in July (less than 25 percent of normal) were in east-central Alabama, western Georgia, southwest North Carolina, and along the east coast of Florida. Eastern portions of Virginia and North Carolina continued to remain dry, with July precipitation between 25 and 75 percent of normal.
  • There were 737 reports of severe weather across the Southeast in July. As in June, the main threat from severe storms was damaging straight-line winds. A 78 mph (126 km/hr) wind gust was reported at the Donaldson Industrial Airpark near Greenville, SC on the 26th of the month and a 69 mph (111 km/hr) gust was reported at Augusta Bush Field in Georgia on the 27th of the month. In Georgia, there were numerous reports of lightning-related damage and at least two fatalities from cloud-to-ground strikes. Only 8 tornadoes were reported across the Southeast in July. Three of these reports, including one EF-1, occurred near Lancaster, SC on the 12th of the month. Several downed trees were reported with only minor damage to homes and buildings. The remaining tornadoes were reported in North Carolina, including multiple reports of a single tornado on the 26th of the month in northwest North Carolina near the town of Low Gap.
  • In terms of drought, the area of abnormally dry conditions (D0) expanded in July, particularly across parts of Alabama and Georgia. By the end of the month, more than half of the Southeast displayed D0 or greater conditions. The combination of hot, dry conditions throughout much of Virginia and northeast North Carolina resulted in broad areas of moderate drought (D1) with localized areas experiencing severe drought (D2) conditions. By the end of the month, D1 conditions were observed across portions of western North Carolina and northwest South Carolina. Much of western Alabama, central Georgia, Florida, and the central Carolinas remained drought-free in July. The hot, dry weather lead to continued reductions in crop yields across the region (e.g., corn and soybeans in North Carolina and Virginia; cotton in Georgia). Further rainfall deficits across the Florida Panhandle are likely to result in reductions in peanut and cotton crop yields, which are reaching critical levels for water demand. In contrast, the heat and lack of rain contributed to a more productive grape harvest in Virginia, which benefited local wineries.
  • For more information, please go to the Southeast Regional Climate Center Home Page.
  • High Plains Region: (Information provided by the High Plains Regional Climate Center)
  • July 2010 was an active month for the High Plains Region. In addition to a new United States hail record which was set in South Dakota, numerous daily and monthly precipitation records were set across Colorado, Kansas, Nebraska, and South Dakota. Temperatures across the Region, on the other hand, were near normal with temperature departures ranging from 2 degrees F (1.1 degrees C) below normal to 2 degrees F (1.1 degrees C) above normal. Some areas of Colorado and a few other locations scattered through the Region were 2-4 degrees F (1.1-2.2 degrees C) above normal. While most locations were near normal, one location made it into the top 10 warmest Julys on record. Crested Butte, Colorado, which is located in the west central part of the state, tied for its 4th warmest July. The average temperature in Crested Butte was 60.4 degrees F (15.8 degrees C) which was 4.4 degrees F (2.4 degrees C) above normal. This was close to, but could not beat out the warmest July on record which occurred in 1966 with an average temperature of 61.0 degrees F (16.1 degrees C) (period of record 1910-2010).
  • July 2010 was a wet month for portions of Colorado, Kansas, Nebraska, and South Dakota. Southeastern South Dakota and northeastern Nebraska, where precipitation was 200-300 percent of normal, were hit particularly hard and flooding along many rivers continued into August. The abundance of moisture this month led numerous locations to be ranked in the top 10 wettest Julys on record and at least 5 of these locations recorded their wettest July. Within the first week of July locations in Kansas, Colorado, and Nebraska were already ranked in the top 10 wettest Julys on record. Heavy rain in the panhandle of Nebraska led to flooding and evacuations in the town of Lodgepole. Dodge City, Kansas set a new record for the greatest 24-hour precipitation when 6.95 inches (176.53 mm) of precipitation fell in less than 24 hours on July 4-5. Dodge City went on to record its second wettest July with 8.40 inches (213.36 mm) of precipitation. This total was just shy of the record 9.13 inches (231.90 mm) which fell in 1962 (period of record 1875-2010). July 23rd was an active day in South Dakota. Storms produced high winds, flooding, tornadoes and record breaking hail. According to the National Weather Service in Aberdeen, South Dakota, a record breaking hailstone fell in Vivian, South Dakota and measured 8 inches in diameter, weighed 1.9375 pounds, and had a circumference of 18.62 inches. The previous record hailstone, by weight, fell in Coffeyville, Kansas September 3, 1970 and weighed 1.67 pounds. The previous record hailstone, by diameter, was the 7 inch Aurora, Nebraska hailstone which fell June 22, 2003. The Aurora hailstone retains the record for largest circumference at 18.75 inches. Later in the month, due abundant monsoonal moisture, the Trinidad Perry Stokes Airport, Colorado recorded its wettest July with 6.84 inches (173.74 mm) of precipitation. This beat out the old record of 6.55 inches (166.37 mm) received in 1981 (period of record 1948-2010). Interestingly, earlier this year this location also recorded its wettest February and wettest March. Through July 31st, the year-to-date precipitation total at the Trinidad Perry Stokes Airport was 16.51 inches (419.35 mm), which makes 2010 already the 10th wettest year on record.
  • While some areas of the High Plains Region received record setting precipitation, other areas were still experiencing either abnormally dry or drought conditions. Abnormally dry conditions (D0) in Colorado were unchanged in the north and trimmed down in the south, while D0 were expanded north from Oklahoma into Kansas. Large changes occurred this month in western Wyoming as a reassessment of conditions caused the severe drought conditions (D2) to be downgraded to moderate drought conditions (D1). The remaining D1 areas were downgraded to D0. North Dakota, South Dakota, and Nebraska remained drought free. According to the U.S. Seasonal Drought Outlook released July 15th, the drought conditions in western Wyoming were expected to persist through October 2010.
  • For more information, please go to the High Plains Regional Climate Center Home Page.
  • Southern Region: (Information provided by the Southern Regional Climate Center)
  • With the exception of western Oklahoma and western Texas, July was a relatively warm month throughout the southern region. The most anomalously warm area of the southern region was western and eastern Tennessee. The state reported a monthly average temperature of 80.00 degree F (26.67 degrees C), which was the tenth warmest July on record (1895-2010). Both Louisiana and Mississippi experienced their thirteenth warmest July on record (1895-2010). Mississippi had a monthly average temperature of 82.50 degrees F (28.06 degrees C), whereas in Louisiana, the average temperature for the month was 83.10 degrees F (28.39 degrees C). Arkansas experienced its twenty-second warmest July, with a state wide average temperature for the month of 81.90 degrees F (27.72 degrees C). Temperature conditions were slightly cooler than normal through much of western Texas, with moth states averaging between 1 to 3 degrees F (0.56 to 1.67 degrees C) below normal. In Oklahoma conditions were relatively near normal, with slightly cooler than normal temperatures in the west and slightly warmer than normal temperatures in the east.
  • July precipitation totals varied spatially across the southern region. In northern Arkansas, many stations reported over twice the monthly normal. Many stations in the north central and north eastern part of the state received over 7 inches (177.80 mm) for the month. In the southern part of the state, however; precipitation totals were generally below normal, with many stations reporting between 50 to 90 percent of normal. Similar dryness was also observed in western Oklahoma, central Tennessee, as well as eastern and north western Mississippi. In Texas and eastern Oklahoma, conditions were quite wet, with a bulk of the stations reporting over 200 percent of normal for the month. In Houston, the station at Houston Heights, for example, reported a total of 18.54 inches (470.92 mm) of precipitation, or 14.96 inches (379.98 mm) above normal. Near Lubbock, Texas, the station at Post, Texas reported 14.59 inches (370.59 mm) of precipitation, which was 12.56 inches (319.02 mm) above normal. Many stations in western and southern Texas reported over 7 inches (177.80 mm) of precipitation for the month of July. The state of Texas averaged 5.18 (131.57 mm) inches for the month, which was their fourth wettest July on record (1895-2010). For Oklahoma, which averaged 4.59 inches (116.59 mm) of precipitation, it was the fifteenth wettest July on record (1895-2010).
  • Drought conditions in the Southern Region have changed slightly over the past month. High July monthly precipitation totals throughout most of Texas has led to improved conditions there. In particular, the north central and eastern regions of the state have seen significant improvements. As of June 29, 2010, approximately 14 percent of the state was experiencing moderate drought or worse. As of August 3, 2010, that value has decreased to only 2.45 percent. There has also been an almost complete removal of severe drought conditions in Texas. Elsewhere, drought conditions have deteriorated slightly in south eastern Mississippi, with moderate drought being introduced into the Natchez area.
  • On July, 1, 2010, two tornadoes were reported in Aransas County, Texas. The twisters were reported to have blown out some windows. A third tornado was spotted on that day in Kleberg County, Texas, however; there was no mention of damage or injuries.
  • On July 24, 2010, the remnants of tropical storm Bonnie made landfall in southern Louisiana as a tropical depression. The storm did not produce strong winds, however; heavy rainfall was reported in West Baton Rouge Parish. Many homes in the Lynndale subdivision of the town of Port Allen, Louisiana were inundated with up to four inches of water. Radar estimates indicate that a stalled thunderstorm dropped approximately 5 to 7 inches (127.00 to 177.80 mm) of rain in the area, causing some minor flash flooding.
  • On July 26, 2010, a tornado touched down seven miles north of Nashville, Tennessee. Approximately 12 brick homes suffered heavy roof damage. In addition, two buildings were impaled by two by fours.
  • For more information, please go to the Southern Regional Climate Center Home Page.
  • Western Region: (Information provided by the Western Regional Climate Center)
  • Temperatures throughout the West were near normal with the northern half slightly below normal and the southern half slightly above. Coastal California had some very low average maximum temperatures due to a persistent marine layer all month. Downtown San Francisco had its coolest average July maximum temperature (63.1 deg F, 17.3 deg C) since 1971. Only one day there reached 70 deg F (72 deg F on the 3rd) and for the last 14 days no day exceeded 64 deg F. San Diego's monthly average of 65.9 deg F (18.8 deg C) was the coolest July since 1933. Preliminary estimates of the mean monthly maximum temperature along the central coast show the lowest July daytime readings in 116 years.
  • Most of the west measured below normal rainfall except for parts of the southwest and eastern Montana. Although the southwest monsoon started about a week later than usual it made up for it quickly with heavy rain during the latter half of the month. Flagstaff measured 5.94 inches of rain making it the third wettest July dating back to 1924. Cloudcroft, New Mexico, measured 12.21 inches (310 mm) making it the second wettest July on record dating back to 1902.
  • July 1: Hailstorm in Montana: Although the hailstorm occurred on June 30th in the Bozeman area, the damage was not determined until the following day. Damage from the golf ball to tennis ball sized hail was estimated to be $60 million in Bozeman.
  • July 20: Mudflows in Arizona: Heavy rain over the San Francisco Peaks near Flagstaff fell on the area burned last month in the Schultz Fire causing large mudflows and killing one 12 year old girl who fell into a flooded wash. Water, mud and ash covered roads and inundated numerous homes in the area.
  • July 21: Lightning in Grand Tetons, Wyoming: Sixteen climbers were rescued over an eight hour rescue operation after they became injured by a midday thunderstorm. Eight of the climbers were treated for injuries sustained by nearby lightning and one person died falling off a cliff.
  • July 22-23: Flooding in eastern Alaska: Heavy rain fell over the Forty Mile River Basin in eastern Interior Alaska causing numerous washouts, mudslides and slumping road beds along the Taylor Highways from Chicken to Eagle. Northway, 6.12 inches (155 mm) reported its 2nd wettest July since 1942 (behind 6.42 inches / 163 mm in 2005). O'Brien Creek on the Taylor Highway noted 6.4 inches of rain (163 mm).
  • July 26: Tornado in Northeastern Montana: Supercells in northeast Montana spawned one tornado, three inch hail and 70 mph winds. A 10-year old boy and his 46-year old uncle were killed by the tornado (later rated an EF3) near Reserve, MT. Nearly 6 miles of power lines were downed. This tornado was rated one of the strongest and the most deadly in Montana history and the strongest tornado to hit the state since 1988.
  • July Fires: Numerous fires burned in the western states but the most significant were those in California where many homes were destroyed. The West Fire near Tehachapi began on the 27th and within 12 hours more than 20 homes had been lost with another 150 structures threatened. By the end of July a total of 25 homes had been destroyed and over 1,400 acres burned. In northern Kern County the Bull Fire, which began on the 26th, had burned more than 16,000 acres by the end of the month with roughly 85% containment. This fire had destroyed 8 residences. Between these two fires over 2,300 people in the area had been evacuated. The year has been rather quiet for fires, with 2.0 million acres (0.81 million hectares) burned (52 percent of the 10-year average of 3.89 million acres / 1.57 million hectares), and 38,000 fires compared with the 10-year mean of 51,000.

See NCDC's Monthly Records web-page for weather and climate records for the month of May. For additional national, regional, and statewide data and graphics from 1895-present, for any period, please visit the Climate at a Glance page.

PLEASE NOTE: All of the temperature and precipitation ranks and values are based on preliminary data. The ranks will change when the final data are processed, but will not be replaced on these pages. Graphics based on final data are provided on the Climate Monitoring Products page and the Climate at a Glance page as they become available.

Citing This Report

NOAA National Centers for Environmental Information, Monthly National Climate Report for July 2010, published online August 2010, retrieved on July 18, 2024 from https://www.ncei.noaa.gov/access/monitoring/monthly-report/national/201007.