Mosquito season in Clay County, MN: when it starts and ends
Mosquito months in Clay County
In a normal year mosquito season in Clay County, MN starts around May 1 and ends around October 5, about 22 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 17.
- Book any yard treatment for early May, ahead of the July peak.
- Repellent can go away after October 5.
- 30 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to July, and check MN spray notices.
Clay County against the rest of MN
Clay County has the 53rd longest season of 87 MN counties, at 157 days against 176 in Winona County and 118 in Cook County. Its mean temperature is 42°F.
- Wilkin County: May 1 to October 6 (158 days, 6 WNV)
- Lincoln County: May 2 to October 7 (158 days, 2 WNV)
- Douglas County: May 2 to October 6 (157 days, 6 WNV)
- Dodge County: May 2 to October 5 (156 days, 1 WNV)
West Nile in Clay County
From 1999 to 2025, CDC ArboNET counted 67 human West Nile cases in Clay County (25 neuroinvasive) across 16 years. The worst was 2016 with 11; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.