Mosquito season in Iowa County, IA: when it starts and ends
Mosquito months in Iowa County
In a normal year mosquito season in Iowa County, IA starts around April 19 and ends around October 17, about 26 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Iowa County, and when
- Start tipping out standing water weekly by April 5.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 17.
- No West Nile cases since 2016, so bites in Iowa County are a nuisance; check window screens.
Iowa County against the rest of IA
Iowa County has the 43rd longest season of 99 IA counties, at 181 days against 198 in Des Moines County and 160 in Worth County. Its mean temperature is 48.2°F.
- O'Brien County: April 18 to October 18 (182 days, 5 WNV)
- Harrison County: April 19 to October 18 (182 days, 7 WNV)
- Story County: April 19 to October 17 (181 days, 8 WNV)
- Carroll County: April 20 to October 18 (181 days, 3 WNV)
West Nile in Iowa County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Iowa County (0 neuroinvasive) across 1 year. The worst was 2002 with 1; the latest was 2002.
Background: when mosquitoes go away for the winter; how the dates are worked out.