Mosquito season in Clearwater County, MN: when it starts and ends

Mosquito months in Clearwater County

In a normal year mosquito season in Clearwater County, MN starts around May 9 and ends around September 29, about 20 weeks.

1. Jan
2. Feb
3. Mar
4. Apr
5. May
6. Jun
7. Jul
8. Aug
9. Sep
10. Oct
11. Nov
12. Dec

What to do in Clearwater County, and when

• Start tipping out standing water weekly by April 25.
• Book any yard treatment for early May, ahead of the July peak.
• Repellent can go away after September 29.
• No West Nile cases since 2016, so bites in Clearwater County are a nuisance; check window screens.

Clearwater County against the rest of MN

Clearwater County has the 79th longest season of 87 MN counties, at 143 days against 176 in Winona County and 118 in Cook County. Its mean temperature is 38.9°F.

• Todd County: May 8 to October 1 (147 days, 5 WNV)
• Beltrami County: May 9 to September 30 (144 days, 0 WNV)
• Lake of the Woods County: May 9 to September 29 (143 days, 0 WNV)
• Itasca County: May 10 to September 29 (142 days, 5 WNV)

West Nile in Clearwater County

CDC ArboNET lists no human West Nile cases for Clearwater County from 1999 to 2025, though virus turned up in birds, mosquitoes or horses in 4 of those years.

Background: when the season starts across the US; how the dates are worked out.