Midwest Averages Above Normal Temperatures, 16th Coldest February on Record
Average temperature for the Midwest during 2021 was 50.6°F, which was 1.6°F above the 1991-2020 average (Figure 1). Based on final data, 2021 ranked the 8th warmest dating back to 1895. All nine Midwestern states were warmer than normal in 2021, ranging from 0.6°F above normal in Kentucky to 2.6°F above normal in Minnesota. The upper Midwest had the greatest temperature departures, with Michigan having the 3rd warmest year on record and both Minnesota and Wisconsin having the 7th warmest year on record (Figure 2). March (8th), June (6th, tie), October (4th), and December (8th) all ranked among the top-10 warmest for the Midwest. February had the largest temperature departures of any month in 2021 at 8.4°F below normal (Figure 3). Based on final data, February ranked the 16th coldest on record.
North-South Divide on 2021 Precipitation
Annual precipitation for the Midwest was 36.61 inches, which was 1.34 inches below the 1991-2020 average. This is the lowest annual precipitation in the Midwest since 2012. Based on final data, 2021 ranked as the 48th wettest since 1895. Annual statewide precipitation totals varied across the region with a clear north-south divide (Figure 4). Precipitation totals were 0.45 inches to 3.09 inches above normal in Illinois, Indiana, Kentucky, Missouri, and Ohio (Figure 5). Below normal annual precipitation ranging from -1 inch to -4.6 inches was measured in Iowa, Michigan, Minnesota, and Wisconsin. Minnesota and Wisconsin had their first year since 2012 with below average annual precipitation. Regionwide, October was the 7th wettest on record and November was the 16th driest on record dating back to 1895.
Drought conditions touched every state across the Midwest, except Kentucky, at some point during 2021. The most widespread, severe, and long-lasting drought conditions were seen across the northern and western portions of the region. Drought intensity peaked, primarily affecting Minnesota and Iowa, in August 2021. Exceptional (D4) drought was denoted in Minnesota for the first time since the U.S Drought Monitor began in 2000. On August 24th, 97 percent of Minnesota was in drought with 58 percent of the state classified as D3 (extreme) or D4 (exceptional) (Figure 6). Dry conditions throughout the northwest portion of the region stressed crops, threatened livestock, and reduced water availability. The St. Cloud dam (in Minnesota) had to turn off its generators for the first time since the drought of 1988 after water levels dropped to just 4 feet deep on the Mississippi River. Conditions gradually began to improve in Minnesota and Iowa throughout the fall, closing the year with limited areas of D1 (moderate) drought in Iowa and D2 (severe) drought in northern Minnesota. Extreme northern Illinois and much of Wisconsin ended 2021 with D1 (moderate) drought conditions as well (Figure 7).
Significant Severe Weather Events
The Midwest had an unusually quiet severe weather season during spring and early summer. Activity increased during the second half of the year with notable severe weather outbreaks on July 14 (Iowa) (Figure 8) and October 24 (Missouri and Illinois) (Figure 9). The year’s most impactful and widespread severe weather came in two separate events during December. The December 10th severe weather outbreak moved across Illinois, Indiana, Kentucky, Missouri, and Ohio producing 59 preliminary tornado reports and 234 high wind reports (Figure 10). The Midwest had at least 65 confirmed fatalities and about 100 injuries. Among the dozens of confirmed tornadoes that day included one long-track EF-4 tornado affecting Kentucky that was on the ground for 165.7 miles, had peak winds of 190 mph, and resulted in 55+ fatalities. Five EF-3 tornadoes were confirmed, including one that killed six people inside a heavily damaged Amazon facility in Illinois. A derecho on December 15th spawned over 70 tornadoes and destructive thunderstorms in Iowa, Minnesota, and Wisconsin killing at least two people (Figure 11).
Heavy rains in southern and eastern Kentucky in late February caused record flooding on a portion of the Kentucky River. Thirteen counties declared flood emergencies as numerous highways were closed and water rescues ensued. Flooding due to heavy rainfall stretched from Missouri northeastward to Michigan on June 25th and 26th. Significant flooding closed dozens of roads across northwest Missouri. One fatality was reported in Clinton County, Missouri after a vehicle became stranded in flood waters. This same storm system led to flash flooding over the Chicago metropolitan area as 2 inches of rain fell in just a few hours. Michigan Governor Gretchen Whitmer declared a state of emergency due to excessive flooding on June 26th. On August 12th, Gibson City, Illinois received a remarkable 10 inches of rain in just 6 hours leading to widespread flooding throughout the community. An intense storm system on October 24th and 25th brought 2 inches to 4 inches of rainfall through an area from Iowa to southern Michigan and northwest Ohio. These storms pushed numerous streams in Illinois, Indiana, and southern Michigan, to near flood stage or minor flood stage. Flooding along these river systems continued through the rest of October (Figure 12).
Late Spring and Fall Freezes for Midwest
The last spring freeze was 2-3 weeks later than normal in the Midwest, with some locations across the upper Midwest seeing freezing temperatures into the last week of May. Poplar Bluff, Missouri, had its fourth-latest subfreezing temperature since 1897. The first fall freeze was 2-4 weeks later than normal across the Midwest, with several record late first fall freezes. International Falls, Minnesota had the latest first freeze since 1897.
An early spring warm-up paired with drier-than-normal conditions allowed farmers to begin fieldwork and crop planting earlier-than-normal. However, a late spring cold-snap along with continued dry conditions led to delayed and uneven crop development. Growing conditions turned more favorable throughout the season, allowing corn and soybeans to recover from early season damage. Corn and soybeans matured rapidly in late summer and early fall, prompting an early start to harvest. Crops dried quickly in fields, catching farmers by surprise and reducing the demand for drying and propane costs. Normal-to-dry conditions kept corn and soybean harvest ahead of schedule in the northwest whereas harvest slowed in the southeast due to excessive October wetness.