- For December, the average contiguous U.S. temperature was 35.7°F, 3.1°F above the 20th century average. This ranked in the warmest third of the 126-year period of record.
- December was a warm month across parts of the West, Northern Tier, central Plains, Great Lakes and Northeast. North Dakota ranked fourth warmest while Montana, South Dakota and Maine ranked fifth warmest in the 126-year record.
- Below-average temperatures were present in portions of the Four Corners region, Lower Mississppi Valley and Southeast during December.
- Alaska ranked in the warmest third of the December record with a statewide average temperature of 10.6°F, 6.9°F above the long-term average. The warmest departures from average occurred across much of the Panhandle and portions of northern Alaska. Some below-average temperatures were observed across the Aleutians during December.
- The nationally averaged maximum temperature (daytime highs) was warmer than average during December at 46.7°F, 3.9°F above average, ranking as the tenth warmest December in the 126-year record. Much of the West, Northern Tier, central and southern Plains, Great Lakes and Northeast had maximum temperatures which were much-above-average for the month. Portions of the Gulf Coast, Southeast and central Rockies had daytime high temperatures that were below average during December.
- The nationally averaged minimum temperature (overnight lows) during December was 24.8°F, 2.2°F above average and ranked in the warmest third of the 126-year record. Above-average overnight temperatures were observed across the span of the Northern Tier as well as parts of the West Coast. Below-average temperatures occurred across portions of the Southwest, Deep South, Gulf Coast and the Southeast.
- Warm records in December outpaced cold records by a seven-to-one margin. As of January 12, there were 3,855 warm daily high (2,855) and low (1,000) temperature records tied or broken during December. There were approximately 547 daily cold high (283) and low (264) temperature records set during the month.
- Based on NOAA's Residential Energy Demand Temperature Index (REDTI), the contiguous U.S. temperature-related energy demand during December was 67 percent of average and ranked as the 25th lowest value on record.
- The December precipitation total for the contiguous U.S. was 1.99 inches, 0.36 inch below average, and ranked in the driest third of the 126-year period of record.
- Above-average precipitation occurred across parts of the central and southern Plains and from the Mid-Atlantic to New England.
- Below-average precipitation dominated the West, northern Plains, Great Lakes, Ohio Valley and the Southeast.
- According to the December 29 U.S. Drought Monitor report, approximately 49 percent of the contiguous U.S. was in drought, which is one percent higher than at the beginning of December. Drought conditions expanded or intensified across portions of the West as well as parts of the northern and central Plains and Texas. Drought severity and/or extent lessened across the Northeast.
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)
- For the seventh consecutive month, the Northeast experienced above-normal temperatures. The region had its 19th warmest December on record with an average temperature of 31.2 degrees F (-0.4 degrees C), 2.8 degrees F (1.6 degrees C) above normal. All twelve Northeast states experienced above-normal temperatures, with average temperatures ranging from 0.3 degrees F (0.2 degrees C) above normal in West Virginia to 5.9 degrees F (3.3 degrees C) above normal in Maine. This December ranked among the 20 warmest on record for six states: Maine, fifth warmest; Vermont, 12th warmest; New Hampshire, 15th warmest; Massachusetts and New York, 17th warmest; and Rhode Island, 19th warmest. On December 1, Caribou, Maine, recorded a high temperature of 60 degrees F (16 degrees C), its warmest winter temperature on record. On the same day, Caribou had a low temperature of 50 degrees F (10 degrees C), its warmest minimum temperature for winter on record.
- December was a wetter-than-normal month in the Northeast with the region receiving 4.49 inches (114.05 mm) of precipitation, 129 percent of normal. Vermont was the lone drier-than-normal state seeing 99 percent of normal precipitation. Precipitation for the other states ranged from 115 percent of normal in New York to 180 percent of normal in Rhode Island. Six states ranked this December among their 20 wettest on record: Rhode Island, fifth wettest; Delaware, eighth wettest; Massachusetts, ninth wettest; Maryland, 14th wettest; Connecticut, 19th wettest; and New Hampshire, 20th wettest.
- The U.S. Drought Monitor from December 1 showed 21 percent of the Northeast in a moderate, severe, or extreme drought and 33 percent of the region as abnormally dry. Extreme and severe drought lingered in northern New England. Of the twelve Northeast states, eight had moderate drought conditions present and ten had areas of abnormal dryness. However, wetter-than-normal weather during December helped alleviate drought and abnormally dry conditions in much of the Northeast. The December 29 U.S. Drought Monitor showed four percent of the Northeast in a moderate drought and 19 percent of the region as abnormally dry. These areas included portions of northern New England, New York, and Pennsylvania.
- A rapidly-intensifying nor’easter dropped rain and snow and produced gusty winds in the Northeast from December 5 to 6. The greatest rain totals of 3 to 5 inches (76 to 127 mm) were in southeastern Maryland and eastern Massachusetts, while the greatest snow totals of over 12 inches (30 cm) were in northern and western Maine, central New Hampshire, and central Massachusetts, where thundersnow was reported. The highest wind gusts ranged from 40 to 70 mph, particularly in coastal areas from New York’s Long Island up to Maine. Heavy snow and/or strong winds brought down limbs and wires, resulting in power outages. In fact, around 230,000 customers in Maine, more than a quarter of the state, lost power. Numerous accidents shut down Interstate 84 in Connecticut. A historic snowstorm dropped snow on almost every part of the Northeast from December 16 to 17. Storm snow totals exceeded 24 inches (61 cm) in an area stretching from central Pennsylvania through New York and into northern New England, where snow fell at rates of at least 3 to 4 inches (8 to 10 cm) per hour. The highest snowfall totals of 40 to 44 inches (102 to 112 cm) were reported in central New York, eastern Vermont, and western New Hampshire. Two-day snowfall totals ranked as the largest on record for any month at Binghamton, New York, which saw 40.0 inches (101.6 cm) of snow, and Williamsport, Pennsylvania, which picked up 24.7 inches (62.7 cm). Concord, New Hampshire, saw 24.2 inches (61.5 cm) on December 17, making it the site’s all-time snowiest day on record and qualifying as the largest December snowstorm. In addition, December 17 became the snowiest December day on record for Binghamton, with 26.4 inches (67.1 cm), and Albany, New York, with 19.7 inches (50.0 cm). For several other locations in the Northeast, the storm’s daily or two-day snow total ranked among the ten greatest for December or any month on record. Portions of West Virginia and the Mid-Atlantic also saw freezing rain, with ice accumulations of up to 0.41 inches (10.41 mm), and sleet. Wind gusts of up to 62 mph (28 m/s) accompanied the storm in coastal areas, where minor to moderate flooding occurred. The storm contributed to hundreds of vehicles crashes, including a pileup involving more than 65 vehicles on Interstate 80 in central Pennsylvania. In addition, Interstate 81 near Binghamton, New York, was shut down for several hours due to disabled vehicles. Another storm system trekked through the Northeast from December 24 to 25. Between 1 inch (25 mm) and 4 inches (102 mm) of rain fell across most of the region, with locally higher amounts of up to 6 inches (152 mm) in New York’s Catskills. Several locations had one of their 10 wettest December days on record. In areas of northern Pennsylvania and central and eastern New York that had seen record snowfall just a week prior, the combination of heavy rain and melting snow led to flooding. There were reports of flooded roads, some evacuations, and a few homes taking on water. Wet antecedent conditions also led to widespread minor to moderate flooding, with locally major flooding, in southeastern Pennsylvania and Delaware. There were numerous closed roads and multiple water rescues. Wind gusts of up to 71 mph (32 m/s) were recorded in coastal areas from New Jersey to southern New England, downing trees and wires and damaging a few buildings. The storm, as well as lake-effect behind the system, dropped snow on portions of West Virginia, western Pennsylvania, and western New York. The greatest snow totals were up to 30 inches (76 cm) in northwestern Pennsylvania and up to 24 inches (61 cm) 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)
- December temperatures ranged widely across the Midwest. In Kentucky and southern Ohio temperatures were near normal while western Minnesota saw temperatures that were 6 to 10 degrees F (3 to 6 C) above normal. Region-wide temperatures were 30.2 degrees F (-1.0 C), which was 4.2 degrees F (2.3 C) above normal. This ranked among the top-25 warmest Decembers since 1895. Minnesota ranked as the 13th warmest December and Michigan and Wisconsin also ranked among the top-25 warmest. A large part of the warmth was due to maximum temperatures rather than minimum temperatures. Daily record high temperatures in December numbered over 400, with the vast majority of those (375) being record high maximum temperatures versus just 35 record high minimum temperatures. Many of the new records were set on December 10th and 11th when warmth was widespread across the region. Maximum temperatures on those two days were at least 10 degrees F (5.6 C) above normal for nearly all of the Midwest and more than 20 degrees F (11.1 C) above normal in southern Illinois and southern Indiana where temperatures were above 60 degrees F (15.6 C).
- December precipitation was below normal for most of the Midwest. A large swath from central and southern Missouri to the western edge of Lake Erie was more than 1.00 inches (25 mm) below normal. Smaller areas of slightly above-normal conditions were scattered around the region, the largest in southeastern Iowa. Only a tiny area in northern Minnesota exceeded 125 percent of normal while areas with less than 50 percent of normal touched every state except Kentucky. The region ranked as the 25th driest December on record since 1895 with 64 percent of the normal precipitation. Statewide values ranged from 53 percent of normal in Wisconsin to 76 percent of normal in Kentucky.
- Annual temperatures ranked as the 12th warmest year in 2020, while precipitation ranked as 37th wettest since 1895. The 2020 regional average temperature was 49.9 degrees F (9.9 C), which was 1.2 degrees F (0.7 C) above normal. All nine states ranked among the warmest 20 percent of their histories, with temperatures ranging from 0.9 to 1.8 degrees F (0.5 to 1.0 C) above normal. Precipitation ranged more widely across the region with Iowa (-5.84 inches or -148 mm) and Minnesota (-3.75 inches or 95 mm) well below normal, Indiana slightly below normal (-0.04 inches or -1 mm), five states at 1.00 to 3.00 inches (25 to 76 mm) above normal, and Kentucky with 9.97 inches (253 mm) above normal. Viewed as a percentage of normal, the state values ranged from just 83 percent of normal in Iowa to 121 percent of normal in Kentucky. The region as a whole was above normal, the eighth straight year to record above-normal precipitation.
- Drought was fairly steady in December. Moderate drought expanded slightly, from about 9 percent to 12 percent of the region. The increased area was largely in northern Missouri and central Illinois. However, severe drought (about 2.25 percent) and extreme drought (0.45 percent) remained about the same throughout the month. The dry conditions in December were somewhat offset by limited water demand, keeping the drought status relatively stable.
- Snowstorms impacted the Midwest on several occasions in December. The first of these storms traversed the Upper Midwest on December 11th to 14th, bringing moderate to heavy snow to Iowa, southern Wisconsin and Michigan. Most of the snow fell through the morning of December 12th, with lingering snow and lake-effect snow until the morning of December 14th. Amounts of 6 to10 inches (15 to 25 cm) were reported, with isolated higher amounts. Two more major winter storms brought heavy snow to the northern half of the Midwest during the holiday season. The first of these storms brought heavy snow to Minnesota, northwestern Iowa, northwestern Wisconsin and the Great Lakes from December 23rd to 25th. Moderate snow fell through the morning of December 28th before the second major storm impacted the entire northern half of the Midwest on December 29th and 30th. Heavier bands of snow were recorded in east-central Iowa through northern Illinois. Lesser amounts of lake-effect snow were reported through December 31st as the storm dissipated. These two storms brought a total of more than 12 inches (31 cm) of snow to central Minnesota, east-central Iowa, and northwestern Illinois. Lake-effect snow in Michigan was even higher, with a report of 31.9 inches (81 cm) in the U.P. of Michigan. In total, more than 200 daily snowfall records were broken across the Midwest in December.
- 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 near average to below average across the Southeast region during December, but were near average to above average in Puerto Rico and the U.S. Virgin Islands. Monthly mean temperatures were within 2 degrees F (1.1 degrees C) above and below average for nearly 80 percent of the 178 long-term (i.e., period of record equaling or exceeding 50 years) stations across the region. Relatedly, very few extremes in monthly mean temperature were observed, as only 3 long-term stations were ranked within their ten warmest or coldest values on record. However, Florida observed a below-average monthly mean temperature for the first time since March 2018. The warmest weather of the month occurred on the 13th, as unseasonably warm, moist air surged northward ahead of an approaching cold front. Daily maximum temperatures exceeded 70 degrees F (21.1 degrees C) across portions of every state in the region, with numerous locations across the Florida Peninsula reaching 80 degrees F (26.7 degrees C) or higher. In contrast, the coldest weather of the month occurred on the 25th and 26th, as a departing extratropical cyclone ushered in unusually cold, dry air from Canada. Daily minimum temperatures fell below 30 degrees F (-1.1 degrees C) as far south as northern Florida, with numerous locations across interior portions of the region reaching the teens F (-10.6 to -7.2 degrees C). Dropping to 16 degrees F (-8.9 degrees C) on the 26th, Greensboro, NC (1903–2020) ended its longest streak of 694 consecutive days with a daily minimum temperature at or above 20 degrees F (-6.7 degrees C), surpassing the previous record by 277 days. In addition, many locations across the region observed their coldest Christmas Day in at least two decades. With a daily maximum temperature of 24 degrees F (-4.4 degrees C), Asheville, NC (1876–2020) recorded its coldest Christmas Day since 1983, while Huntsville, AL (1907–2020) observed its coldest Christmas Day since 1985, with a daily maximum temperature of 32 degrees F (0 degrees C). With a daily maximum temperature of 35 degrees F (1.7 degrees C), Atlanta, GA (1878–2020) recorded its coldest Christmas Day since 1989, while Orlando, FL (1892–2020) observed its coldest Christmas Day since 1995, with a daily maximum temperature of 53 degrees F (11.7 degrees C).
- Precipitation was variable across the Southeast region during December, with a few wet extremes recorded. The driest locations were found across portions of coastal South Carolina, west-central and coastal Georgia, central and southern Alabama, the western half of the Florida Panhandle, east-central Florida, the northern half of Puerto Rico, and the U.S. Virgin Islands. Monthly precipitation totals ranged from 50 to less than 25 percent of normal in these areas. In contrast, the wettest locations were found across much of Virginia, as well as portions of North Carolina, southern Florida, and Puerto Rico. Monthly precipitation totals ranged from 150 to more than 200 percent of normal in these areas. Several long-term stations observed December precipitation totals that were ranked within their five highest values on record, including Richmond, VA (1887–2020; 6.62 inches, 168 mm), Williamsburg 2 N, VA (1948–2020; 6.37 inches, 162 mm), Washington Dulles International Airport, VA (1960–2020; 5.81 inches, 148 mm), and Winchester 7 SE, VA (1912–2020; 5.34 inches, 136 mm). Measurable snowfall was generally confined to the higher elevations across the Southern Appalachian Mountains. Beech Mountain, NC (1991–2020), Mt. Mitchell, NC (1925–2020), and Burkes Garden, VA (1896–2020) recorded 16.7, 16.3, and 14.1 inches (424, 414, and 358 mm) of snowfall during the month, which is 4.0, 3.2, and 6.5 inches (102, 81, and 165 mm) above their long-term averages, respectively. However, Washington, D.C. (1884–2020) only recorded a trace of snowfall during the month, which is 2.9 inches (74 mm) below its long-term average. On the 16th, a winter storm produced freezing rain, sleet, and snow across portions of North Carolina, Virginia, and Washington, D.C. Freezing rain accumulations of 0.05 to as much as half of an inch (1 to as much as 13 mm) occurred in central and western portions of North Carolina, as well as southwestern, central, and northern parts of Virginia. Snowfall totals of 2 to more than 8 inches (51 to more than 203 mm) were found across portions of northern Virginia, with the greatest accumulation of 11.5 inches (292 mm) measured in Bayse, VA. About 200 vehicle crashes and 125 disabled vehicles were reported by the Virginia State Police along I-81 and across northern Virginia. In addition, about 36,000 homes and businesses in Virginia were without power following the height of the storm. On the 24th and 25th, a winter storm produced 3 to more than 6 inches (76 to more than 152 mm) of snowfall across the higher elevations of western North Carolina and southwestern Virginia, with the greatest storm total accumulation of 13.6 inches (345 mm) recorded near Hot Springs, NC. Early on the 25th, snow flurries were reported as far south as Charleston International Airport, SC, which is only its second trace of snowfall on Christmas Day since 1938. In addition, Augusta, GA (1871–2020) observed only its second trace of snowfall on Christmas Day since records began 149 years ago. With 1.1 inches (28 mm) of snow on the 25th, Asheville, NC (1869–2020) observed its fifth highest snowfall on Christmas Day since records began 151 years ago.
- There were 85 severe weather reports across the Southeast during December, which is nearly double the median monthly frequency of 43 reports during 2000–2019. Nearly 90 percent (75 of 85) of the severe weather reports during the month were for strong thunderstorm winds. On the 24th and 25th, an extensive squall line associated with a vigorous cold frontal passage produced convective wind gusts exceeding 45 mph (20 m/s) along coastal portions of the region, including 49 mph (22 m/s) at Charleston International Airport, SC, 59 mph (26 m/s) at Brunswick Golden Isles Airport, GA and Tampa International Airport, FL, 61 mph (27 m/s) at Newport News/Williamsburg International Airport, VA, and 64 mph (29 m/s) at Billy Mitchell Airport on Cape Hatteras, NC. In addition, a 55-mph (25-m/s) wind gust reported at Gainesville Regional Airport, FL was the highest gust observed during the month of December since records began in 1973, breaking the old record of 46 mph (21 m/s) set on December 24, 2014. Ten tornadoes (2 EF-0s, 7 EF-1s, 1 EF-2) were confirmed across the region during the month, which is near the median frequency of 9 tornadoes observed during December from 2000–2019. On the 16th, an EF-2 tornado with estimated peak winds of 125 mph (56 m/s) tracked over thirteen miles across Pinellas and Hillsborough Counties in the Tampa Bay area of Florida. The greatest damage occurred at an industrial park, where two buildings were destroyed, and five buildings sustained major damage. In addition, major damage was reported for several buildings at a boat storage facility, with large 2-ton boats tossed around. This was the strongest tornado to hit Pinellas County since October 1992 and the strongest December tornado in Florida since 2006.
- Drought conditions (D1 and greater) were not observed across the Southeast region during December. However, abnormally dry (D0) conditions persisted across portions of Alabama, Georgia, South Carolina, and northern Florida during the month. By the end of the month, over one-third of Georgia was covered with abnormally dry conditions. In addition, a few small pockets of moderate (D1) drought developed in north-central Puerto Rico during late December. Heavy rainfall during early December saturated vegetable fields in southern Florida, resulting in crop losses, increased disease pressure on lettuce and beans, and bloom dropping in pepper and tomato plants. Vegetable and citrus growers in southern Florida had to pump excess water out of their fields due to the persistent rainfall. While cotton producers in the Florida Panhandle continued their harvest, some noted that cotton yields were particularly poor this year from excessively wet weather. In Georgia, winter grazing and small grains benefitted from timely rainfall during the month, but their growth was slowed by cold weather. In central and eastern portions of South Carolina, heavy rainfall delayed the harvesting of row crops and the planting of small grains and cover crops. Prolonged saturated soil caused some farmers to abandon portions of their soybean and cotton fields. Wet weather continued to delay field work across North Carolina, with reports of negative impacts on the wheat crop due to waterlogged soils. Several nights of frost and freezing temperatures during the month caused some grass damage in pastures across northern and central Florida, while low-lying areas of pastures in southern Florida sustained flooding. Pasture conditions in Georgia suffered from freezing temperatures and heavy rainfall during the month. Persistent rainfall in the Pee Dee region of South Carolina caused some health issues in livestock, including coccidia, pneumonia, and salmonella.
- For more information, please visit the Southeast Regional Climate Center Home Page.
High Plains Region (Information provided by the High Plains Regional Climate Center)
- The winter season began on a warm note, a pattern that was evident throughout the High Plains in November. A few locations that broke into the top 10 of warmest Novembers last month also reached the top 10 of warmest Decembers on record. One example is Valentine, Nebraska, which had its 4th warmest November and 5th warmest December (period of record 1889-present). A few snowstorms traversed the region, but large portions of the High Plains were left dry. The dryness led to a lack of snowfall, and without a snowpack, temperatures were much higher than normal. As a result, drought intensified across these areas, and given that it is difficult to get widespread improvements in conditions during the winter, much of the region will likely begin the spring planting season with dry soils.
- The intensifying drought and depleted soil moisture continued to cause impacts across the region. Ski resorts in Colorado were still in desperate need of snow. While fire activity dwindled in Colorado and Wyoming, two fires ignited in the Black Hills on the 23rd. One of these fires, named the American Center Fire, burned approximately 50 acres. According to the South Dakota State Fire Meteorologist, it became the second largest December wildfire in the Black Hills since record-keeping began in 1987. Fire weather conditions were ideal at the time of ignition, as above-normal temperatures occurred ahead of a strong cold front that brought extremely gusty winds. As for agriculture, winter wheat was not faring very well in Colorado. According to the latest USDA Colorado Crop Progress Report, 34 percent of the winter wheat crop was in poor or very poor condition. Dry soils and the lack of snow cover contributed to these conditions. However, winter wheat was faring better in Nebraska and Kansas, with only 15 percent and 17 percent of the crop in poor or very poor condition, respectively. Nationwide, the U.S. winter wheat condition index was the lowest since 2012 at the beginning of December. Livestock producers throughout the region were also being negatively impacted by conditions, as feed and water supplies were limited.
- The pattern of above-normal temperatures that began in November continued into December for the majority of the High Plains region. With the exception of western Colorado, where temperatures were slightly below normal, departures ranged from 3.0-9.0 degrees F (1.7-5.0 degrees C) above normal across the region. It was especially warm in North Dakota, as departures of 9.0-12.0 degrees F (5.0-6.7 degrees C) above normal were common. Numerous locations throughout the High Plains ranked among the top 10 warmest Decembers. For instance, Dickinson, ND, Mobridge, SD, and Sheridan, WY all had their 3rd warmest December on record (Dickinson period of record 1938-present, Mobridge period of record 1911-present, Sheridan period of record 1907-present).
- For most of the region, the greatest temperature departures came in the first week of December, exceeding 25.0 degrees F (13.9 degrees C) above normal in some places. Several locations throughout the Dakotas, Nebraska, and eastern Wyoming set new daily records for maximum temperature on the 8th, with areas of South Dakota, Nebraska, and Kansas setting similar records on the 9th. Sheridan, Wyoming reached 72.0 degrees F (22.2 degrees C) on the 8th, which was not only a daily record maximum temperature, but Sheridan’s 3rd highest December temperature on record. Dickinson, North Dakota also had its 3rd highest December temperature on record when it reached 62.0 degrees F (16.7 degrees C) on the 22nd. The lack of snowpack across these areas was likely the primary cause for unusually warm December temperatures, as snowpack tends to keep temperatures down.
- Much of the region remained dry during December, with many areas receiving less than 70 percent of normal precipitation. The driest areas included western North Dakota, northwestern South Dakota, and north-central Kansas where precipitation was less than 25 percent of normal. However, there were very few locations that had record-breaking dryness. Chadron, Nebraska tied for its 10th driest December on record (period of record 1941-present). This is not too surprising though given that winter is the driest time of the year in the Plains.
- Due to the lack of precipitation, many locations in the High Plains region contended with a lack of snowfall in December. Notable areas that did not get much snow included western North Dakota, northern and western South Dakota, and northern Wyoming. While it is not uncommon for some areas of the High Plains to receive little snowfall in December, there were a couple noteworthy records. For instance, the Newell COOP station in South Dakota received only a trace amount of snowfall, tying for its 2nd least snowiest December on record (period of record 1920-present). Meanwhile, the Bowman COOP station in North Dakota had its 7th least snowiest December, receiving only 0.2 inch (1 cm) (period of record 1915-present).
- On the other hand, pockets of wetness existed in central Nebraska, southern Kansas, and central and eastern Colorado where precipitation exceeded 150 percent of normal. Snowstorms moving across the region were primarily responsible for above-normal precipitation in these areas. A couple of systems moved through southern Kansas during the first half of the month, bringing impressive snow totals. For instance, the Ashland COOP station in Kansas received 7.0 inches (18 cm) of snow from a storm on the 3rd, then got 8.0 inches (20 cm) of snow from a different storm on the 13th. By the end of the month, Ashland had received 17.0 inches (43 cm), which was its 2nd snowiest December on record (period of record 1900-present). Several CoCoRaHS stations in southern Kansas reported more than 20.0 inches (51 cm) of snow in December. On the 29th, a storm system brought snowfall to much of Nebraska and southeastern South Dakota. Many locations in eastern Nebraska received at least 6.0 inches (15 cm) of snow. Roads became covered with ice and snow, and some roads were closed, including Interstate 80 in the Nebraska Panhandle.
- Dry conditions caused the Upper Missouri Basin mountain snowpack to get behind in December. According to the U.S. Army Corps of Engineers, as of January 3rd, Snow Water Equivalent (SWE) above Fort Peck Reservoir was 81 percent of average, while the reach between Fort Peck and Garrison Reservoirs was 82 percent of average. Other than a few basins in northwestern Wyoming and south-central Colorado, snowpack was below normal throughout these two states. However, it is still very early in the mountain snowpack season, and there is plenty of time for these areas to catch up. In the Plains, areas with snow on the ground at the end of December were mostly confined to the eastern Dakotas and eastern Nebraska. Warm and dry conditions resulted in snow-free areas across the western Dakotas, western Nebraska, much of Kansas, and the plains of Colorado and Wyoming.
- Overall, drought conditions worsened throughout the High Plains in December. According to the U.S. Drought Monitor, the area experiencing drought (D1-D4) increased from approximately 76 percent to 82 percent over the course of the month. However, the area experiencing abnormal dryness and drought (D0-D4) remained the same at 96 percent.
- The majority of changes in drought conditions occurred early in the month, which is reflected on the December 1st U.S. Drought Monitor map. Many areas experienced degradations in drought conditions due to mounting precipitation deficits and depleted soil moisture. For instance, extreme drought (D3) was introduced to central North Dakota, while moderate drought (D1) spread across southern South Dakota and northern Nebraska. However, beneficial precipitation fell in late November in areas of Kansas and Nebraska, resulting in improvements in drought conditions. Severe drought (D2) was reduced in northeastern Kansas and southeastern Nebraska, while D1 was trimmed in central Kansas.
- While there were some minor adjustments to drought conditions in other areas of the High Plains states throughout December, the drought depiction changed very little after the first week of the month. Now that winter is setting in, soil moisture will likely be “locked in” until spring, making it very difficult for conditions to change drastically throughout the next few months. Timely precipitation in the spring will be critical for easing drought conditions across the region.
- 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 December varied spatially across the Southern Region. Parts of eastern, central, and western Tennessee; central Arkansas; northern, eastern, and southern Mississippi; southern and central Louisiana; and western Texas experienced temperatures 0 to 2 degrees F (0.00 to 1.11 degrees C) below normal. Conversely, parts of central and western Tennessee; western and northern Mississippi; southern, central, western, and eastern Arkansas; northern and western Louisiana; eastern, central, and western Oklahoma; and northern, central, western, southern, and eastern Texas experienced temperatures 0 to 2 degrees F (0.00 to 1.11 degrees C) above normal, while parts of northern Arkansas; northern, central, southern, eastern, and western Oklahoma; and northern, central, and southern Texas experienced temperatures 2 to 4 degrees F (1.11 to 2.22 degrees C) above normal. The statewide monthly average temperatures were as follows: Arkansas – 42.80 degrees F (6.00 degrees C), Louisiana – 50.90 degrees F (10.50 degrees C), Mississippi – 46.60 degrees F (8.11 degrees C), Oklahoma – 41.00 degrees F (5.00 degrees C), Tennessee – 39.80 degrees F (4.33 degrees C), and Texas – 48.30 degrees F (9.06 degrees C). The statewide temperature rankings for December were as follows: Arkansas (forty-sixth warmest), Louisiana (fifty-sixth warmest), Mississippi (fifty-ninth coldest), Oklahoma (forty-second warmest), Tennessee (fifty-eighth warmest), and Texas (forty-eighth warmest). The region as a whole experienced its forty-ninth warmest December on record. All state rankings are based on the period spanning 1895-2020.
- Precipitation values for the month of December varied spatially across the Southern Region. Parts of northern, central, western, and southern Texas received 50 percent or less of normal precipitation. Parts of northern and western Texas received 25 percent or less of normal precipitation, while parts of northern and western Texas received 5 percent or less of normal precipitation. In contrast, parts of northern Louisiana, northern and western Oklahoma, southern Arkansas, and eastern and western Texas received 130 percent or more of normal precipitation. Parts of northern Oklahoma as well as western and eastern Texas received precipitation 150 percent or more of normal, while parts of western Texas received precipitation 200 percent or more of normal. The statewide precipitation totals for the month were as follows: Arkansas – 4.30 inches (109.22 mm), Louisiana – 5.19 inches (131.83 mm), Mississippi – 4.67 inches (118.62 mm), Oklahoma – 2.19 inches (55.63 mm), Tennessee – 4.40 inches (111.76 mm), and Texas – 1.76 inches (44.70 mm). The statewide precipitation rankings for December were as follows: Arkansas (sixtieth wettest), Louisiana (fifty-seventh wettest), Mississippi (fifty-second driest), Oklahoma (thirty-second wettest), Tennessee (fifty-seventh driest), and Texas (fiftieth wettest). The region as a whole experienced its sixtieth driest December on record. All state rankings are based on the period spanning 1895-2020.
- At the end of December, drought conditions improved and deteriorated across the Southern Region. Exceptional drought conditions expanded and persisted across western and northwestern Texas, but exceptional drought conditions were removed from south-central Texas. Extreme drought conditions persisted across parts of Oklahoma and Texas, with new areas developing or expanding across western, southern, and central Texas. However, extreme drought conditions were removed across part of northern Texas. Severe drought classifications expanded across northern, western, southern, and central Texas. Moderate drought classifications expanded or developed across north-central and eastern Texas, northern Mississippi, and western Tennessee, while moderate drought conditions persisted across parts of Oklahoma, Texas, Arkansas, and Mississippi. However, moderate drought conditions were reduced or eliminated across parts of southwestern Arkansas, northwestern Mississippi, and northern and southeastern Texas. There was an increase in the overall area experiencing abnormally dry conditions, with conditions developing or expanding across northern and eastern Arkansas, western Tennessee, northern Louisiana, and northern Mississippi. There was improvement across western Oklahoma, northern and southeastern Texas, southeastern Louisiana, and southern Mississippi as abnormally dry conditions improved or were eliminated.
- In December, there were approximately 45 storm reports across Louisiana, Mississippi, and Texas. There were 16 tornado reports and 29 wind reports. Mississippi tallied the most tornado (13) and wind (14) reports. Unsurprisingly, Mississippi tallied the most reports (27) while Arkansas, Oklahoma, and Tennessee did not tally a single report. Mississippi and Texas were the only states to report tornadoes.
- On December 3, 2020, there were 12 wind reports across Louisiana and Mississippi. Multiple trees and power lines were blown down, while a wind gust of 62 mph (99.78 kph) was reported near Alexandria, Louisiana.
- On December 19, 2020, an injury was reported near Beaumont, Texas after multiple recreational vehicles were overturned due to strong winds.
- On December 23, 2020, there were 15 tornado reports across Mississippi (13) and Texas (2), with these tornadoes reported as having EF-0 or EF-1 intensity. No injuries were reported. Additionally, there were several reports of damage to trees, power lines, and structures due to strong winds.
- On December 30, 2020, a tornado was reported near Corsicana, Texas. Multiple mobile homes were damaged with complete roof removal as well as several trees blown down. No injuries were reported.
- For more information, please visit the Southern Regional Climate Center Home Page.
Drought and Severe Weather:
Western Region (Information provided by the Western Region Climate Center)
- December brought widespread dry conditions to the western United States as a persistent ridge of high pressure centered over the western U.S. deflected storms northward into the Pacific Northwest, British Columbia, and the Alaskan Panhandle. After receiving 0.04 in. (1 mm) of rain on December 17, Las Vegas completed its longest run of dry days on record (since 1948) with 240 consecutive days. Roswell, NM tied its driest December since 1920 with 0.00 in. (0 mm; 0% of normal) of precipitation measured. Bozeman Gallatin Field, MT measured 0.06 in. (1.54 mm; 11% of normal) of precipitation, the driest December since records began in 1941. Precipitation was closer to normal in the Pacific Northwest, with wetter-than-normal conditions in northern coastal Washington. 6.82 in. (173 mm; 162% of normal) of precipitation fell at Bellingham, WA making for the 9th wettest December since 1949. Above-normal temperatures were observed in the northern Pacific Northwest and Intermountain West and below-normal temperatures in the eastern Great Basin and Four Corners region. December was the 9th coldest since 1970 at Farmington, NM with an average temperature of 27.6°F (-2.44°C), which was -3.2°F (-1.8°C) below normal. Regionally, the hottest temperature anomalies in December occurred in Montana. With an average temperature of 27.2°F (-2.67°C; +10.9°F (+6°C) above normal) Glasgow, MT experienced its 4th warmest December since records began in 1947.
- Dry conditions led to the onset of snow drought conditions in many regions of the west. At month’s end, Arizona, New Mexico, California, Utah, Oregon, Colorado and the southern portions of Idaho, Wyoming, and Montana all reported below-normal snowpacks. Snow conditions improved in the northern-most tier of the west, with Washington, northern Idaho, Wyoming, and Montana showing near to above-normal snowpacks. The Sangre de Christo Range of Colorado and New Mexico demonstrated a notable north-to-south gradient, with well-below normal snow conditions in New Mexico improving to above normal in Colorado.
- December was warmer than normal in Hawaii, aided by sea surface temperatures running 1.8-3.6°F (+1-2°C) above normal. On the Island of Hawaii, Hilo, underwent its warmest December in 72 years (record keeping started in 1949) with a mean temperature of 75.4°F (24.1°C), which is +2.2°F (+1.2°C) above normal. On Maui, Kahului experienced its 2nd warmest December since records began in 1905 with a mean temperature of 76.1°F (24.5°C; +2.8°F (+1.6°C) above normal). Conditions were also generally dry on all the islands. Kahului tied its 6th driest December with 0.18 in (4.57 mm; 5% of normal) of precipitation. With 0.31 in. (7.9 mm; 10% of normal) of rain, Honolulu, HI observed its 8th driest December since 1949.
- December over mainland Alaska was generally drier than normal, with the north and west coasts and the Panhandle experiencing wetter-than-normal conditions. Barrow, AK, where records began in 1901, measured 0.70 in. (18 mm; 500% of normal) of precipitation for its 3rd wettest December. On the south coast, Kenai observed only 0.2 in. (5 mm; 15% of normal) of precipitation, making December the 5th driest since record keeping started in 1899. A total of 12.74 in. (323 mm; 218% of normal) of precipitation fell in Juneau, bringing the 2nd wettest December since records started in 1936. Much of Alaska was warmer than normal in December. With mean temperatures of 41.9°F (5.5°C; +4.9°F (+2.7°C) above normal), December was the 3rd warmest in Stika, AK, where records began in 1944. The Chukchi Sea iced over on December 17th, which is the fourth latest in the satellite era. Ice extent in the Bering Sea was 46% of the 1981–2010 average and the third lowest of record for December.
- Significant Events for December 2020
- December 1–2: Extreme rainfall produces mass movements in the Alaskan Panhandle: Strong and concentrated poleward atmospheric moisture transport in the form of a landfalling atmospheric river brought heavy rainfall to the Alaskan Panhandle at the start of December. Over the course of two days, the Haines Airport measured 10.26 in. (260 mm) of precipitation and Juneau Airport set a one-day precipitation record of 5.08 in. (129 mm). This storm helped Haines achieve its wettest December since records began in 1911 with a monthly total of 18.5 in. (470 mm; 300% of normal). The extreme rainfall combined with appreciable snowmelt to saturate soils and increase pore pressures. This resulted in widespread landsliding and flooding impacting 21 communities in Southeast Alaska, along with high elevation avalanches. One avalanche generated a seiche that damaged homes at Chilkat Lake. Many roads and homes were damaged or destroyed by debris flows and landslides with two people presumed dead.
- December 1–31: Persistent Dry Weather Exacerbates Western Drought: Normally a key month during the west’s wet season for rainfall and mountain snow accumulation, drier-than-normal conditions during December 2020 provided little-to-no respite from ongoing drought conditions. Dry conditions were favored by the presence of above normal geopotential heights over the western U.S. (a blocking ridge) and persistent region of low pressure in the Bering Sea. As of December 29, the U.S. Drought Monitor reports over 88% of the west is experiencing some form of drought, with nearly half the west (46%) in Extreme to Exceptional Drought and 22% in Exceptional Drought. With snowpack in many major river basins (e.g., the Colorado and Sacramento River Basins) sitting below normal and a dry fall leading to very low soil moistures at the start of winter, concerns are growing about the potential for a well-below normal spring runoff season if the remainder of the winter and spring are dry.
- For more information, please go to the Western Regional Climate Center Home Page.