Mosquito season in Norman County, MN: when it starts and ends
Mosquito months in Norman County
In a normal year mosquito season in Norman 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 Norman 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.
- 3 West Nile cases since 2016 (last 2018): you should use repellent at dusk July, more so if over 60.
Norman County against the rest of MN
Norman County has the 66th longest season of 87 MN counties, at 150 days against 176 in Winona County and 118 in Cook County. Its mean temperature is 40°F.
- Otter Tail County: May 5 to October 3 (151 days, 9 WNV)
- Chisago County: May 6 to October 4 (151 days, 2 WNV)
- Mahnomen County: May 5 to October 2 (149 days, 0 WNV)
- Marshall County: May 5 to October 1 (149 days, 4 WNV)
West Nile in Norman County
From 1999 to 2025, CDC ArboNET counted 16 human West Nile cases in Norman County (3 neuroinvasive) across 7 years. The worst was 2007 with 7; the latest was 2018.
Background: when mosquitoes go away for the winter; how the dates are worked out.