The statewide average precipitation for 2008 was 50.7 inches, 11.4 inches above normal and the 2nd wettest year since 1895. Only 1993 was wetter with 51.2 inches. See the maps for the annual precipitation total, departure, and percent of normal.
The statewide average temperature for 2008 was 50.6 degrees, 1.1 degrees below normal and the 18th coolest year since 1895. See the map for temperature departures.
December 2008 was both colder and wetter than normal. The statewide average precipitation for December was 4.5 inches, 1.8 inches above normal and the 8th wettest December since 1895. The statewide average temperature for December was 26.3 degrees, 3.5 degrees below normal and the 24th coolest December since 1895.
What are the historical odds for a white Christmas? The odds range from barely 10 percent in far southern Illinois to over 50% in far northern Illinois. See the map and table.
November in Illinois was both cooler and drier than normal. However, a storm system at the end of the month brought the first significant snowfall of the season across northern and central Illinois. See the November press release.
The first significant snow of the season fell in the lake-effect snow belt of the Great Lakes on Nov. 17-18. While Illinois missed most of it, northwestern Indiana reported some sizeable amounts including 10.5 inches in Valparaiso. Below are a couple of places to monitor snowfall reports in Illinois and North America. By the way, Nov. 16-22 was winter preparedness week. Check out the new snowfall page.
While far northern Illinois saw freezing temperatures early in the month, the official close to the 2008 growing season at most locations occurred on October 28. Cold Canadian air pushed across the Midwest, producing lows that morning in the mid to upper 20s across Illinois. For most locations, this was about 1 to 2 weeks behind the normal dates of the first fall frost (32 degrees). Normal dates ranges from October 7in northern Illinois, October 14 in central Illinois, and October 21 in southern Illinois.
For October, the statewide precipitation was 2.6 inches, 0.4 inches below normal. The statewide average temperature was 54.2 degrees, only 0.4 degrees below normal. Overall, moderate weather conditions were quite favorable for farmers harvesting corn and soybeans. See the press release.
Based on preliminary data, the state-wide average precipitation for September was 7.9 inches, making this the third wettest September on record (going back to 1895) for Illinois. The all-time record is 1926 with 9.7 inches while second place goes to 1911 with 9.1 inches. See more on the rains of September.
Chicago (at O'Hare airport) reported 6.64 inches on September 13, setting a new record for the most rain in one calendar day in Chicago's history. The old record was 6.49 inches on August 14, 1987. Chicago climate records date back to 1871.
Based on preliminary numbers, this was the 16th driest August on record for Illinois with 2.3 inches, 1.4 inches below normal. This ends the 8-month streak of above-normal precipitation in Illinois that started in December 2007. The year to date precipitation is 35.1 inches, still 8 inches above normal and the 4th wettest January-August on record. The statewide temperature for August was 71.9 degrees, 1.7 degrees below normal. See the press release for more details.
This was the wettest January-July on record for Illinois with 32.8 inches, 9.4 inches above normal. State-wide July precipitation was 6.3 inches, 2.5 inches above normal. Every month since December 2007 has had above-normal precipitation. See the press release for more information on the impacts on agriculture.
Heavy rains in Illinois and across the Midwest have led to considerable problems with flooding, starting in January and continuing through June. While the more severe flooding has occurred in Iowa, several rivers in or along the border of Illinois flooded as well. See more on the flooding and heavy rains of 2008.
This year has been much more active in terms of severe weather compared to last year. This year Illinois had 47 tornado reports compared to only 23 for 2007. In addition there have been 502 hail and 861 wind damage reports. See more on the severe weather of 2008.