Mosquito season in Cook County, MN: when it starts and ends
Mosquito months in Cook County
In a normal year mosquito season in Cook County, MN starts around June 2 and ends around September 28, about 17 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Cook County, and when
- Start tipping out standing water weekly by May 19.
- Book any yard treatment for early June, ahead of the August peak.
- Repellent can go away after September 28.
- No West Nile cases since 2016, so bites in Cook County are a nuisance; check window screens.
Cook County against the rest of MN
Cook County has the 87th longest season of 87 MN counties, at 118 days against 176 in Winona County and 118 in Cook County. Its mean temperature is 38.8°F.
- St. Louis County: May 13 to September 26 (136 days, 7 WNV)
- Lake County: May 16 to September 25 (132 days, 1 WNV)
West Nile in Cook County
CDC ArboNET lists no human West Nile cases for Cook County from 1999 to 2025, though virus turned up in birds, mosquitoes or horses in 2 of those years.
More: how the dates are worked out · when the season starts across the US.