Illinois State Water Survey - Rainfall above Normal over Much of Illinois during Warm September, University of Illinois at Urbana-Champaign

For Immediate Release October 4, 2005
Rainfall above Normal over Much of Illinois during Warm September

Source:    Contact:

Jim Angel - (217) 333-0729, Fax: (217) 244-0220, jimangel@illinois.edu Eva Kingston - (217) 244-7270, Fax: (217) 333-6540, eva@sws.uiuc.edu

 
"September temperatures averaged 70.6^oF statewide (4.4 degrees above normal), making this the seventh warmest September since 1895 and the third warmest September on record in northeastern Illinois. This also is the fourth consecutive month of temperatures above normal and the seventh warmest June–September on record. Temperatures ranged from 97°F degrees at Belleville on September 22 to 32°F at Mt. Carroll on September 29," says State Climatologist Jim Angel of the Illinois State Water Survey (http://www.sws.uiuc.edu), a division of the Illinois Department of Natural Resources.

September rainfall averaged 3.91 inches (0.73 inches above normal), but rainfall since March averaged 18.90 inches, 7.12 inches below normal and Illinois' sixth driest March–September since 1895. While most of the state enjoyed the extra rainfall in September, rainfall north of I-80 was only 2.79 inches, 0.54 inches below normal. Nashville had the highest one-day precipitation total (3.58 inches on September 20). Lebanon had the highest monthly total (10.11 inches).

Across the state, rainfall has remained below normal since March 1. For example, Chicago O'Hare Airport received only 12.8 inches (11.9 inches below normal); Rockford, 16.1 inches (10.5 inches below); Moline, 10.9 inches (16.3 inches below); Peoria, 13.2 inches (11.5 inches below); Quincy, 15.4 inches (10.6 inches below); Springfield, 16.0 inches (8.1 inches below); Champaign, 21.3 inches (6.8 inches below); and Carbondale, 21.7 inches (5.7 inches below).

"While good rains in August and September have alleviated drought conditions in portions of central and southern Illinois, the most severely affected area in northern Illinois remains stubbornly dry. Check the ISWS' special drought Web site for regular updates (http://www.sws.uiuc.edu/hilites/drought/)," says Angel.

Now that October has arrived, the first fall frost becomes a concern for gardeners. Based on 1971–2000 averages, that usually occurs between October 7 (northern Illinois) and October 21 (southern Illinois), with an average date of October 14 in central Illinois (see map at http://www.sws.uiuc.edu/atmos/statecli/Frost/first_fall_frost.htm). An interesting feature of the map is the delay in the first frost date by about a week in the Chicago area, probably due to a combination of the warmer urban setting and the moderating influence of Lake Michigan.

Angel points out that the actual frost date varies quite a bit each year. "For planning purposes, one can expect the first frost within two weeks of those dates," says Angel.