Mosquito season in Clay County, IA: when it starts and ends
Mosquito months in Clay County
In a normal year mosquito season in Clay County, IA starts around April 23 and ends around October 13, about 25 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Clay County, and when
- Start tipping out standing water weekly by April 9.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 13.
- No West Nile cases since 2016, so bites in Clay County are a nuisance; check window screens.
Clay County against the rest of IA
Clay County has the 78th longest season of 99 IA counties, at 173 days against 198 in Des Moines County and 160 in Worth County. Its mean temperature is 46.4°F.
- Sac County: April 23 to October 14 (174 days, 0 WNV)
- Cass County: April 22 to October 12 (173 days, 0 WNV)
- Webster County: April 23 to October 14 (173 days, 1 WNV)
- Cherokee County: April 24 to October 14 (173 days, 3 WNV)
West Nile in Clay County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Clay County (0 neuroinvasive) across 1 year. The worst was 2014 with 1; the latest was 2014.
Background: when the season starts across the US; how the dates are worked out.