Mosquito season in Hancock County, IL: when it starts and ends
Mosquito months in Hancock County
In a normal year mosquito season in Hancock County, IL starts around April 8 and ends around October 27, about 29 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Hancock County, and when
- Start tipping out standing water weekly by March 25.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after October 27.
- No West Nile cases since 2016, so bites in Hancock County are a nuisance; check window screens.
Hancock County against the rest of IL
Hancock County has the 56th longest season of 102 IL counties, at 201 days against 232 in Pulaski County and 174 in Boone County. Its mean temperature is 52.5°F.
- Cass County: April 8 to October 27 (201 days, 0 WNV)
- Douglas County: April 8 to October 27 (201 days, 1 WNV)
- Marshall County: April 8 to October 26 (201 days, 1 WNV)
- Mason County: April 8 to October 26 (201 days, 0 WNV)
West Nile in Hancock County
From 1999 to 2025, CDC ArboNET counted 2 human West Nile cases in Hancock County (1 neuroinvasive) across 2 years. The worst was 2004 with 1; the latest was 2004.
See how the dates are worked out, and when mosquitoes go away for the winter.