Wet October and 9th-coldest on record

[NOV. 8, 2006]  According to the state climatologist, October temperatures were 3.8 degrees below normal and the ninth-coldest October on record. Temperatures across the state dropped to the freezing mark or lower for the first time this fall on Oct. 12 and 13, including a low of 20 degrees at Park Forest on Oct. 12. Those temperatures effectively ended the 2006 growing season. As a result of this cold weather, October heating degree days, a measure of home heating demand, were 38 percent above normal and averaged 462 heating degree days statewide, compared with the normal 335.

The information was provided by Jim Angel of the Illinois State Water Survey, a division of the Illinois Department of Natural Resources.

Preliminary data for Illinois indicate that October's 3.97 inches of rainfall was 1.05 inches above normal. Rainfall has been much above normal in southern, central and northeastern Illinois, especially the Chicago area. On Oct. 3, Midway Airport reported 3.80 inches, the largest one-day rainfall of the month, and the Chicago Botanic Garden reported 7.75 inches, the largest monthly total. The U.S. Drought Monitor depicts the area between Quincy and Moline in western Illinois, where rainfall has been about 25 percent below normal, as being in "moderate" drought, however.

Historically, a colder-than-normal October does not increase the chance for a cold winter. In fact, previous cold Octobers were more likely to be followed by December-February periods with temperatures near normal. The National Weather Service winter outlook still calls for an increased chance of temperatures above normal across Illinois and precipitation below normal in the southern two-thirds of the state, Angel said.

[Illinois State Water Survey news release]