Mosquito season in Peoria County, IL: when it starts and ends
Mosquito months in Peoria County
In a normal year mosquito season in Peoria County, IL starts around April 9 and ends around October 25, about 28 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Peoria County, and when
- Start tipping out standing water weekly by March 26.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after October 25.
- 12 West Nile cases since 2016: you should wear EPA-registered repellent at dusk June to August, and check IL spray notices.
Peoria County against the rest of IL
Peoria County has the 63rd longest season of 102 IL counties, at 199 days against 232 in Pulaski County and 174 in Boone County. Its mean temperature is 52°F.
- Logan County: April 8 to October 25 (200 days, 0 WNV)
- Champaign County: April 9 to October 26 (200 days, 5 WNV)
- De Witt County: April 9 to October 24 (198 days, 0 WNV)
- Henderson County: April 10 to October 25 (198 days, 0 WNV)
West Nile in Peoria County
From 1999 to 2025, CDC ArboNET counted 30 human West Nile cases in Peoria County (24 neuroinvasive) across 13 years. The worst was 2005 with 7; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.