Mosquito season in Winneshiek County, IA: when it starts and ends
Mosquito months in Winneshiek County
In a normal year mosquito season in Winneshiek County, IA starts around April 22 and ends around October 16, about 25 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Winneshiek County, and when
- Start tipping out standing water weekly by April 8.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 16.
- No West Nile cases since 2016, so bites in Winneshiek County are a nuisance; check window screens.
Winneshiek County against the rest of IA
Winneshiek County has the 58th longest season of 99 IA counties, at 177 days against 198 in Des Moines County and 160 in Worth County. Its mean temperature is 47.2°F.
- Ida County: April 21 to October 15 (177 days, 3 WNV)
- Calhoun County: April 22 to October 16 (177 days, 2 WNV)
- Wright County: April 22 to October 16 (177 days, 1 WNV)
- Sioux County: April 21 to October 14 (176 days, 32 WNV)
West Nile in Winneshiek County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Winneshiek County (0 neuroinvasive) across 1 year. The worst was 2002 with 1; the latest was 2002.
Background: when the season starts across the US; how the dates are worked out.