Mosquito season in Jasper County, IL: when it starts and ends
Mosquito months in Jasper County
In a normal year mosquito season in Jasper County, IL starts around April 3 and ends around October 31, about 30 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Jasper County, and when
- Start tipping out standing water weekly by March 20.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after October 31.
- No West Nile cases since 2016, so bites in Jasper County are a nuisance; check window screens.
Jasper County against the rest of IL
Jasper County has the 32nd longest season of 102 IL counties, at 211 days against 232 in Pulaski County and 174 in Boone County. Its mean temperature is 54.2°F.
- Cumberland County: April 3 to October 31 (211 days, 0 WNV)
- Effingham County: April 3 to October 31 (211 days, 1 WNV)
- Fayette County: April 2 to October 30 (210 days, 0 WNV)
- Richland County: April 3 to October 31 (210 days, 1 WNV)
West Nile in Jasper County
From 1999 to 2025, CDC ArboNET counted 3 human West Nile cases in Jasper County (2 neuroinvasive) across 2 years. The worst was 2002 with 2; the latest was 2013.
Background: when mosquitoes go away for the winter; how the dates are worked out.