Illinois State Water Survey - University of Illinois at Urbana-Champaign

Cool, Dry August for Illinois

9/2/2008

Source: Jim Angel (217) 333-0729, Fax: (217) 244-0220, jimangel@illinois.edu
Editor: Lisa Sheppard (217) 244-7270, sheppard@illinois.edu

CHAMPAIGN, Ill. - August statewide precipitation was below normal, ending an eight-month streak of above-normal precipitation in Illinois that began in December 2007, according to State Climatologist Jim Angel of the Illinois State Water Survey (http://www.isws.illinois.edu).

Statewide August precipitation was 2.3 inches, 1.4 inches below normal, and the 16th driest August on record. Combined with above-normal precipitation since the start of 2008, the January-August total was 35.1 inches, still 8.0 inches above normal.

While portions of west-central and southwestern Illinois received near-normal precipitation, drier conditions prevailed in east-central and southeastern Illinois. One of the drier spots was Champaign-Urbana, which received only 0.8 inches, 3.6 inches below normal, and the sixth driest August, according to records extending back to 1889.

Also noticeable was the lack of hot weather. August statewide temperatures averaged 72 degrees, 2 degree below normal.

While Chicago reported one day of 90-degree weather at O'Hare Airport and two days at Midway Airport, most of northern Illinois reported none. Central Illinois sites reported between one and three days, and southern Illinois reported between three and nine days–all below normal.

The National Weather Service (NWS) September forecast calls for an increased chance of below-normal temperatures in the western half of the state, and the remainder of the state has equal chances of above, below, or near-normal temperatures. [See forecast]

The three-month forecast September–November forecast calls for an increased chance of above-normal temperatures and equal chances of above, below, or near-normal precipitation throughout Illinois.

"One of the concerns right now is the threat of an early frost causing damage to late-developing crops. Normal frost dates range from October 7 in northern Illinois and October 14 in central Illinois, to October 21 in southern Illinois. It's too early to tell if an early frost is likely to occur," concludes Angel. [See frost date map]

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