Mosquito season in Pepin County, WI: when it starts and ends
Mosquito months in Pepin County
In a normal year mosquito season in Pepin County, WI starts around April 30 and ends around October 9, about 23 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Pepin County, and when
- Start tipping out standing water weekly by April 16.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 9.
- 1 West Nile case since 2016 (last 2025): you should use repellent at dusk July to August, more so if over 60.
Pepin County against the rest of WI
Pepin County has the 36th longest season of 72 WI counties, at 162 days against 180 in La Crosse County and 139 in Rusk County. Its mean temperature is 45.9°F.
- Chippewa County: April 30 to October 9 (162 days, 2 WNV)
- Dunn County: April 30 to October 9 (162 days, 2 WNV)
- Waupaca County: April 30 to October 9 (162 days, 0 WNV)
- Trempealeau County: April 30 to October 8 (161 days, 7 WNV)
West Nile in Pepin County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Pepin County (0 neuroinvasive) across 1 year. The worst was 2025 with 1; the latest was 2025.
Background: when mosquitoes go away for the winter; how the dates are worked out.