Mosquito season in Otter Tail County, MN: when it starts and ends
Mosquito months in Otter Tail County
In a normal year mosquito season in Otter Tail County, MN starts around May 5 and ends around October 3, about 22 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Otter Tail 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 3.
- 9 West Nile cases since 2016 (last 2025): you should use repellent at dusk July, more so if over 60.
Otter Tail County against the rest of MN
Otter Tail County has the 64th longest season of 87 MN counties, at 151 days against 176 in Winona County and 118 in Cook County. Its mean temperature is 40.8°F.
- Mille Lacs County: May 4 to October 4 (153 days, 3 WNV)
- Becker County: May 5 to October 3 (151 days, 5 WNV)
- Chisago County: May 6 to October 4 (151 days, 2 WNV)
- Norman County: May 5 to October 2 (150 days, 3 WNV)
West Nile in Otter Tail County
From 1999 to 2025, CDC ArboNET counted 29 human West Nile cases in Otter Tail County (15 neuroinvasive) across 12 years. The worst was 2013 with 4; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.