Illinois State Climatologist Office

Recent News/Events

June - Another Wet Month for Illinois

Based on preliminary data for Illinois, the statewide precipitation for June was 5.25 inches, 1.2 inches above normal and the 25th wettest June since statewide records began in 1895 (click on map at right). The precipitation total for the first half of 2009 was 24.2 inches, 4.8 inches above normal and the 14th wettest on record.

The statewide average temperature for June was 72.6 degrees, 0.7 degrees above normal. However, the first half of June was significantly cooler (2.6 degrees below normal) than the second half (4.1 degrees above normal).

Hot, humid weather arrives in Illinois

According to NOAA, heat is the number one weather-related killer. According to one study more than 1,500 people in the US die each year on average from heat. The combination of warm weather and high humidity has caused the NWS to issue heat advisories in Illinois in recent days. So here are some sites with information on summer heat.

• Current Heat Advisories (NWS)
• Heat Index Forecasts (NWS)
• Heat Waves in Illinois
• NOAA Watch
• Center for Disease Control and Prevention (CDC): English and Spanish
• Ready America: English and Spanish
• Latest temperatures and dew point temperature (U of Illinois Dept. Atmospheric Science) - dew point temperatures above 70F are very uncomfortable.

5th Wettest Spring on Record

Based on preliminary data for Illinois, the statewide precipitation this spring was 15.9 inches, 4.5 inches above normal and the 5th wettest spring since statewide records began in 1895 (see map). May precipitation was 6.0 inches, 1.7 inches above normal and the 19th wettest May on record.  Spring includes the months of March, April, and May.

The wettest site this spring has been St. David (near Peoria) with 27.7 inches. The wettest site in May was Edwardsville with 11.7 inches. Both Peoria and Galesburg reported their wettest spring on record, impressive given their much longer period of record.

At 15.9 inches, this spring is almost two inches wetter than the 14.1 inches of last spring (2008). Historically, wet springs do not lead to wet summers. In fact, of the other nine wettest springs in the list below, the rainfall of the following summers was above normal in 4 cases and below normal in 5 cases with an overall average of 1 inch below normal.

Wettest Springs on Record in Illinois

1. 1927 - 18.59"
2. 1945 - 17.32"
3. 1973 - 17.22"
4. 1898 - 16.82"
5. 2009 - 15.86"
6. 1933 - 15.83"
7. 2002 - 15.82"
8. 1908 - 15.65"
9. 1995 - 15.63"
10. 1957 - 15.45"

6th Wettest April on Record

Based on preliminary data for Illinois, the statewide average precipitation was 6.2 inches, 2.4 inches above normal and tied for the 6th wettest April since statewide records began in 1895. This April shares the record with April 1983. The wettest April on record was 7.1 inches in 1957. Normal statewide April rainfall is 3.8 inches.

Cooler than normal temperatures accompanied the wet weather, leading a statewide average temperature of 51.3 degrees (1 degree below normal). While the first 22 days of April were 4 degrees below normal, the last 8 days partially compensated by being 7 degrees above normal.

As of May 1, the 1-5 day forecast from the NWS shows chances of rain across the state almost every day with the southern half of Illinois having the potential of 1 to 4 inches of rainfall. Amounts in the northern half are expected to be less than an inch. The 6-10 day and 8-14 day forecast shows above-normal rainfall. The NWS outlook for May shows an increased chance of above-normal rainfall.

March '09 - Wet in the North, Dry in the South

Based on preliminary data for Illinois, the statewide average precipitation was 4.2 inches, 1 inch above normal (figure on the left - click to enlarge). However, much of that precipitation (both rain and snow) fell in the northern half of Illinois. Some areas received twice their normal March amounts. Meanwhile, drier conditions prevailed in southern Illinois. Some areas in far southern Illinois received only 70 percent of their normal March precipitation.

Overall, March temperatures in Illinois were 2 degrees above normal. Temperature departures in the southern half of the state were 2 to 3 degrees above normal while only 1 to 2 degrees above normal in the northern half.

More images for March: precipitation (percent of normal), snowfall, temperature (departures)

Climate Events of 2009 in Illinois

Find the significant climate-related events of 2009 in Illinois here.

Climate Events of 2008 in Illinois

Find the significant climate-related events of 2008 in Illinois here.