Mosquito season in Mahnomen County, MN: when it starts and ends
Mosquito months in Mahnomen County
In a normal year mosquito season in Mahnomen County, MN starts around May 5 and ends around October 2, about 21 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Mahnomen 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 2.
- No West Nile cases since 2016, so bites in Mahnomen County are a nuisance; check window screens.
Mahnomen County against the rest of MN
Mahnomen County has the 67th longest season of 87 MN counties, at 149 days against 176 in Winona County and 118 in Cook County. Its mean temperature is 39.8°F.
- Chisago County: May 6 to October 4 (151 days, 2 WNV)
- Norman County: May 5 to October 2 (150 days, 3 WNV)
- Marshall County: May 5 to October 1 (149 days, 4 WNV)
- Pennington County: May 5 to October 1 (149 days, 0 WNV)
West Nile in Mahnomen County
From 1999 to 2025, CDC ArboNET counted 2 human West Nile cases in Mahnomen County (1 neuroinvasive) across 2 years. The worst was 2013 with 1; the latest was 2013.
See how the dates are worked out, and when mosquitoes go away for the winter.