Summer - One of the Warmest and Wettest on Record, Illinois State Water Survey

ISWS Press Release

For Immediate Release September 2, 2010
Summer - One of the Warmest and Wettest on Record
Jim Angel - (217) 333-0729,
Lisa Sheppard - (217) 244-7270,

CHAMPAIGN, Ill. - This summer was one of the warmest and wettest on record, based on preliminary data. The statewide average temperature for summer (June‚ÄďAugust) in Illinois was 76.4 degrees, 2.7 degrees above normal and the seventh warmest summer on record, according to State Climatologist Jim Angel of the Illinois State Water Survey (

The average rainfall for summer in Illinois was 16.7 inches, 5.2 inches above normal, ranking as the sixth wettest summer on record. Statewide records extend back to 1895.

The heaviest rains occurred in western and northern Illinois. Bentley (Hancock County) reported the most rain of any location with 28.5 inches. Nine other sites reported over two feet of rain within this timeframe.

The wettest summer on record was 1993 with 18.3 inches. The warmest summer on record was 1936 with an average of 78.6 degrees.

The average statewide temperature for August was 76.8 degrees, 3.2 degrees above normal. That places the month as the 13th warmest August on record.  August was on track to being even warmer, but a late-month cool spell knocked it down a few notches in the ranking.

August rainfall was close to normal with a statewide average of 3.4 inches, just 0.3 inches below normal. However, significant areas in east-central and southern Illinois received less than half that amount. For example, Champaign reported 1.64 inches for the month.

The National Weather Service calls for an increased chance of warmer-than-normal temperatures for Illinois in September. The precipitation outlook for September is neutral (equal chances of above, below, and near-normal rainfall), except for far northern Illinois, which has a slightly higher chance of above-normal rainfall.

The Illinois State Water Survey at the University of Illinois at Urbana-Champaign, a division of the Institute of Natural Resource Sustainability, is the primary agency in Illinois concerned with water and atmospheric resources.

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