Mosquito season in Pennington County, MN: when it starts and ends
Mosquito months in Pennington County
In a normal year mosquito season in Pennington County, MN starts around May 5 and ends around October 1, about 21 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Pennington County, and when
- Start tipping out standing water weekly by April 21.
- Book any yard treatment for early May, ahead of the July peak.
- Repellent can go away after October 1.
- No West Nile cases since 2016, so bites in Pennington County are a nuisance; check window screens.
Pennington County against the rest of MN
Pennington County has the 69th longest season of 87 MN counties, at 149 days against 176 in Winona County and 118 in Cook County. Its mean temperature is 39.7°F.
- Mahnomen County: May 5 to October 2 (149 days, 0 WNV)
- Marshall County: May 5 to October 1 (149 days, 4 WNV)
- Polk County: May 5 to October 2 (149 days, 15 WNV)
- Red Lake County: May 5 to October 2 (149 days, 1 WNV)
West Nile in Pennington County
From 1999 to 2025, CDC ArboNET counted 2 human West Nile cases in Pennington County (0 neuroinvasive) across 2 years. The worst was 2007 with 1; the latest was 2007.
Background: when the season starts across the US; how the dates are worked out.