Midwest Averages Above Normal Precipitation
Annual precipitation averaged across the Midwest was 37.72 inches, 0.78 inches above normal. This was the eighth straight year above the 1981-2010 normal for the region. This ranked as the 37th wettest in history since 1895. Kentucky was the wettest state with 9.97 inches above normal which ranked as the 8th wettest in its history (Figure 1). Three more states had more than 2.00 inches above normal and another two (Illinois and Wisconsin) had more than 1.00 inch above normal. Indiana was barely below normal (-0.04 inches), while Minnesota (-3.75 inches) and Iowa (-5.84 inches) were well below normal. Iowa ranked as the 30th driest in its history. Wisconsin, like the region, has recorded eight straight years above normal. The six Midwest states with above-normal precipitation in 2020 all exceeded their normal annual precipitation by November, and Kentucky did so in October. Iowa had its 3rd driest August in history (Figure 2).
Midwest Experiences Above Normal Temperatures
Temperatures across the region for 2020 averaged 1.2°F above normal. This ranked 2020 as the 12th warmest since 1895, and the warmest year since 2012. All nine Midwest states were above their 1981-2010 normal by 0.9 to 1.8°F. Ohio ranked as the 7th warmest in its history and Michigan ranked 10th (Figure 3). The seven other states ranked between 13th and 26th in their respective histories. Four states (Indiana, Kentucky, Missouri, and Ohio) have had six straight years above normal while the other five states, and the region as a whole, were below normal in 2019. January (9th) and November (7th) were months that ranked among the top-10 warmest for the region while October ranked as the 13th coolest in history. June, July, and December also ranked among the warmest 20 percent (top 25) of history for the region.
Drought Monitor Update
The Midwest was completely free of drought from January through May of 2020. That 21-week stretch extended to a 29-week stretch when the last eight weeks of 2019 were added making it the second longest stretch with no drought in the region since 2000. The only streak longer was during the first 32 weeks of 2019. A streak of 14 straight weeks, from mid-January to mid-April, set a new record with no abnormally dry area in the region. This topped the 12-week stretch in early 2019 with no abnormally dry conditions. Parts of the Midwest ranged from 5-20 weeks of drought for 2020 (Figure 4). Moderate drought first emerged in Minnesota in early June (Figure 5) and by the end of July had touched parts of all nine Midwest states (Figure 6). Severe drought touched parts of the five western-most states and extreme drought affected parts of southwestern Missouri and western Iowa. Parts of northwestern Iowa remained in extreme drought as the year came to an end (Figure 7).
Severe Weather and Flooding
Severe weather in the region was spread across many months, however the most newsworthy was a severe derecho on August 10. Damage was spread across Iowa, Wisconsin, Illinois, Michigan, and Indiana (Figure 8). The highest winds, over 100 miles per hour, were in central Iowa causing severe damage to crops and trees. Millions of acres of crops were flattened by the storm. As the derecho headed east the winds eased slightly but continued to do significant damage in the other states affected. Power outages affected millions in the region with many outages lasting days or even weeks in some cases. There were at least 60 injuries and 4 deaths attributed to the storm system. Two other costly severe weather outbreaks in the Ohio River Valley included one on March 27th-28th and a severe hail storm on April 7th-8th.
Flooding and flash flooding caused fatalities in the Midwest. March 20th saw six flooding deaths in Indiana when bridges were washed out near Laurel, Indiana. Flooding issues were noted especially in eastern Kentucky in February, the Ohio River flood plain in the spring but also along the Mississippi River system. In May, a Midland, Michigan dam failed due to heavy rains over three days, 17th-19th. More than 10,000 residents of Midland were evacuated in less than 12 hours with no loss of life.
Corn and soybean crops in the Midwest had favorable conditions in 2020 except for the areas hit by drought and the derecho. Several Midwest states had record yields for corn and/or soybeans. Corn yields were new records in Minnesota, Wisconsin, Indiana, and Kentucky. Soybean yields set records in both Indiana and Kentucky. Crops largely reached maturity and were harvested after drying down in the field. The lack of a need for supplemental drying was a benefit for farmers. Yield losses in Iowa were due to a combination of drought and damages from the derecho. Good harvest conditions in Iowa limited the loss from the derecho and lodged crops.
Hurricane Cristobal Remnants Reach Wisconsin
The remnants of Hurricane Cristobal moved across the region June 8th-10th. The path taken by the storm system was one of the furthest to the west and north in history. The center of the system moved across Iowa as just the second tropical system to do so. It was also just the third to make it as far north as Wisconsin.
Spring freeze damage was reported in a mid-April freeze despite not being particularly late in the season. An early season freeze event occurred in the Upper Midwest on September 8th-11th. The rapid drop in temperatures, from warm conditions just prior to the freeze, exacerbated the situation.