Mosquito season in Winnebago County, IA: when it starts and ends
Mosquito months in Winnebago County
In a normal year mosquito season in Winnebago County, IA starts around April 26 and ends around October 11, about 24 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Winnebago County, and when
- Start tipping out standing water weekly by April 12.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 11.
- No West Nile cases since 2016, so bites in Winnebago County are a nuisance; check window screens.
Winnebago County against the rest of IA
Winnebago County has the 91st longest season of 99 IA counties, at 168 days against 198 in Des Moines County and 160 in Worth County. Its mean temperature is 45.1°F.
- Hancock County: April 26 to October 12 (169 days, 1 WNV)
- Mitchell County: April 26 to October 11 (168 days, 1 WNV)
- Allamakee County: April 27 to October 12 (168 days, 1 WNV)
- Clayton County: April 27 to October 11 (167 days, 0 WNV)
West Nile in Winnebago County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Winnebago County (1 neuroinvasive) across 1 year. 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.