Mosquito season in Brown County, WI: when it starts and ends
Mosquito months in Brown County
In a normal year mosquito season in Brown County, WI starts around April 30 and ends around October 12, about 23 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Brown 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 12.
- 7 West Nile cases since 2016 (last 2024): you should use repellent at dusk July to July, more so if over 60.
Brown County against the rest of WI
Brown County has the 29th longest season of 72 WI counties, at 164 days against 180 in La Crosse County and 139 in Rusk County. Its mean temperature is 45.2°F.
- Adams County: April 29 to October 10 (164 days, 1 WNV)
- Outagamie County: April 29 to October 11 (164 days, 5 WNV)
- Eau Claire County: April 28 to October 8 (163 days, 3 WNV)
- Polk County: April 29 to October 9 (163 days, 0 WNV)
West Nile in Brown County
From 1999 to 2025, CDC ArboNET counted 17 human West Nile cases in Brown County (14 neuroinvasive) across 10 years. The worst was 2002 with 4; the latest was 2024.
Background: reading the West Nile counts; how the dates are worked out.