Mosquito season in Marshall County, MN: when it starts and ends
Mosquito months in Marshall County
In a normal year mosquito season in Marshall 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 Marshall 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.
- 4 West Nile cases since 2016 (last 2018): you should use repellent at dusk July, more so if over 60.
Marshall County against the rest of MN
Marshall County has the 68th 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.
- Norman County: May 5 to October 2 (150 days, 3 WNV)
- Mahnomen County: May 5 to October 2 (149 days, 0 WNV)
- Pennington County: May 5 to October 1 (149 days, 0 WNV)
- Polk County: May 5 to October 2 (149 days, 15 WNV)
West Nile in Marshall County
From 1999 to 2025, CDC ArboNET counted 8 human West Nile cases in Marshall County (4 neuroinvasive) across 4 years. The worst was 2016 with 3; the latest was 2018.
Background: reading the West Nile counts; how the dates are worked out.