April 16, 2021

State climatologist: Illinois March temperatures and precipitation were above normal

CHAMPAIGN, Ill. — March 2021 was mild and warm, according to Illinois State Climatologist Trent Ford at the University of Illinois’ Illinois State Water Survey.

The preliminary statewide average March temperature was 45.9 degrees, 4.5 degrees above the 1991-2020 average and the 13th warmest on record going back to 1895.

March average temperatures ranged from the low 40s in northern Illinois to low 50s in southern Illinois, which was between 3 and 5 degrees above the 1981-2010 normal.

Twenty daily high maximum temperature records and 16 daily high minimum records were broken statewide. Chicago’s O’Hare Airport recorded a minimum temperature of 57 degrees on March 10, which broke the previous daily high minimum temperature record by 11 degrees.

The persistent warmth during the month accelerated growing degree day accumulation and prompted an earlier than normal spring greening, the result of which was earlier stone fruit blooms. Unfortunately, an early bloom increases the risk of significant freeze damage to vulnerable crops such as peaches and cherries.

Precipitation

Preliminary statewide average total March precipitation was 4.10 inches, 1.16 inches above the 1991-2020 average.

The first third of the month was very dry across the state. Most of the state north of Interstate 64 received less than 0.05 inches of precipitation in the first 10 days of March. A pattern change around the middle of the month brought several rounds of storms and heavier rain to southern and central Illinois.

March total precipitation ranged from just over 1 inch in northeast Illinois to over 5 inches throughout most of southern Illinois.

Southern Illinois soils were previously at or above normal moisture levels coming into March, so the additional precipitation resulted in standing water in fields and minor to moderate flooding along the Big Muddy River and Wabash River, among others in the region. However, the rain was welcome on drier central Illinois soils.

In response to the improvement in moisture conditions in central Illinois, the U.S. Drought Monitor removed all moderate drought in its March 16 map — the first time Illinois was free of drought since August 2020.

Snowfall in March was well below normal statewide because of the mild temperatures. Total March snowfall ranged from less than a quarter of an inch in north-central Illinois to just over 4 inches in northwest Illinois. March snowfall departures ranged from less than an inch below normal in far southern Illinois to nearly 5 inches below normal in northeast Illinois.