Temperature

The average December temperature for the Midwest was 26.1°F, which was 1.6°F below the 1991-2020 normal (Figure 1). Average temperatures were below normal for most of the region, with only northeast Michigan being above normal (Figure 2). Statewide average temperatures ranged from 3.7°F below normal in Minnesota to 0.8°F above normal in Michigan. Active weather patterns throughout the month meant that temperatures were highly variable and wide-ranging from week to week across the region. Notably, subzero temperatures were widespread from December 22-25 (more on that in the Winter Storm section below) followed by a rapid warm-up December 30-31 with temperatures reaching into the 50s and 60s.

Precipitation

December precipitation totaled 2.13 inches for the Midwest, which was 0.07 inches below normal, or 97 percent of normal (Figure 1). Precipitation was 100-300 percent of normal in the northwest, declining to 50-75 percent of normal in the east (Figure 3). Statewide precipitation totals ranged from 1.40 inches below normal in Ohio to 0.82 inches above normal in Minnesota. Minnesota had its 4th wettest December dating back to 1895 (tied with 2019). Numerous stations across Minnesota had a top 10 wettest December, including Duluth which ranked the 6th wettest since records began in 1871. Spencer, Iowa had its wettest December on record going back to 1895. Conversely, Cleveland, Ohio had its 11th driest December dating back to 1871.

Snow

December snowfall totaled 15-50 inches across the upper Midwest, with southeast Michigan seeing less than 10 inches (Figure 4). Across the lower Midwest, snowfall ranged from less than 1 inch up to 5 inches, with the greatest totals in the Ohio River Valley. The upper Midwest was affected by numerous snow-producing weather systems that resulted in above-normal snowfall and multiple lake-effect snow events. A powerful storm brought 10-30 inches of heavy snow to northern Minnesota and northwest Wisconsin from December 13-17 (Figure 5). Duluth, Minnesota had its snowiest December dating back to 1884 with 44.9 inches.

Drought

Drought conditions began to subside in December, with the total area affected by drought declining 7 percent across the month (Figure 6). The most notable improvements were in southern Minnesota and at the confluence of the Ohio and Mississippi Rivers. However, while showing improvement, both of those locations remained in moderate to severe drought. By month’s end, 37 percent of the region was in drought and 30 percent was abnormally dry. The most severe drought conditions were in northwest Iowa, southern Minnesota, and southeast Michigan. All states had at least some areas abnormally dry or in drought.

Winter Storm: December 22-25

An intense Arctic cold front traversed the central US December 22-25 blanketing the region with frigid temperatures, high winds, and snow. Air temperatures plunged sharply and rapidly, with one-day temperature changes of 20-40°F across the lower Midwest. Dangerous wind chills from -20 to -40°F gripped the Midwest as winds gusted 30-50 mph and higher. Chicago and Des Moines clocked over 80 consecutive hours with subzero wind chills. In northwest Minnesota, wind gusts approached hurricane strength with a 74-mph gust recorded in Grand Marais. While snowfall across the lower Midwest was a modest 1-5 inches, high winds caused extensive blowing and drifting that halted ground and air transportation for days. Whiteout conditions caused a 50-vehicle crash on the Ohio Turnpike on December 23 that killed four people. Ten additional weather-related fatalities across four Midwestern states have been reported by media. Localized power outages, broken water mains, and frozen pipes were reported across the region. Across the upper Midwest, snow totals ranged from 3-10 inches, with 20-30 inches in lake-effected areas of northern Michigan.