Mosquito season in Hennepin County, MN: when it starts and ends
Mosquito months in Hennepin County
In a normal year mosquito season in Hennepin County, MN starts around April 25 and ends around October 11, about 24 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Hennepin County, and when
- Start tipping out standing water weekly by April 11.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 11.
- 67 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to August, and check MN spray notices.
Hennepin County against the rest of MN
Hennepin County has the 8th longest season of 87 MN counties, at 169 days against 176 in Winona County and 118 in Cook County. Its mean temperature is 45.6°F.
- Martin County: April 25 to October 13 (171 days, 6 WNV)
- Rock County: April 25 to October 12 (170 days, 7 WNV)
- Watonwan County: April 26 to October 12 (169 days, 2 WNV)
- Brown County: April 26 to October 11 (168 days, 1 WNV)
West Nile in Hennepin County
From 1999 to 2025, CDC ArboNET counted 118 human West Nile cases in Hennepin County (72 neuroinvasive) across 19 years. The worst was 2025 with 19; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.