A wet April extended the trend for above-average precipitation in Illinois. This year was the seventh-wettest December-to-April period on record, according to Brian Kerschner, a spokesperson for the Illinois State Climatologist Office at the Illinois State Water Survey, part of the Prairie Research Institute at Illinois.
The preliminary statewide average precipitation for April was 4.58 inches, which is 0.80 inches above the long-term average.
An active spring weather pattern resulted in a majority of regions in northern, eastern and southern Illinois receiving more than 100% of average monthly precipitation, with localized amounts approaching 200%. Smaller regions of the state in west-central Illinois, roughly between the Mississippi and Illinois rivers, are the only locations to receive near- or below-average precipitation for the month.
The heaviest precipitation fell in extreme southern Illinois, especially in counties bordering the Wabash and Mississippi rivers, where 6 to more than 8 inches was common. The highest total in the state was reported at a station near Cobden in Union County with 8.31 inches.
Heading into May, flooding is an ongoing concern for the state, as soil moisture remains in the 90th to 95th percent range.
As of April 30, 134 river gauges affecting Illinois were reported with crests in minor, moderate or major flood stages. The greatest threat continues to remain along the Mississippi River. Flooding concerns were intensified by several days of heavy rain during the last week of April.
April snowfall occurred primarily during two short-lived, yet notable, late-season events that affected northern portions of the state.
The first snow event on the weekend of April 13-14 brought widespread reports of 1 to 5 inches along a corridor extending from near Quincy and running northeast toward Chicago and the Illinois/Wisconsin border. Several localities west and north of Chicago reported from 6 to more than 8 inches of snow. Notable accumulations were measured as far south as Peoria.
An accumulation of 5.4 inches at Chicago’s O’Hare International Airport tied the record for the snowiest calendar day this late in the season. April 16, 1961, also recorded 5.4 inches of snow.
On April 27, a second snow event brought a variety of wintry precipitation types to locations in northern Illinois, including another round of accumulating snow for many from Chicago and points north and west. With 3.7 inches, this was the latest snow event with 2 or more inches on record for Rockford.
The maximum monthly snowfall in Illinois was reported at a station near St. Charles in Kane County with an impressive 13.5 inches.
Despite several significant temperature swings throughout the month, which are common during springtime, statewide April temperatures finished right around the long-term average. The preliminary average statewide April temperature was 52.0 degrees, which is 0.6 degrees below the long-term average.
A few pockets in extreme southern Illinois reported slightly above-average temperatures, and sporadic regions in northern Illinois reported temperatures of slightly below the long-term average. This is a welcome change from last year, which ranked as the second-coldest April on record.
The highest temperature in the state was recorded at a station near Jerseyville in Jersey County with a reading of 85 degrees on April 23. In contrast, the lowest temperature of 18 degrees was recorded at a station in Altona in Knox County on April 1.
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