Mosquito season in Bayfield County, WI: when it starts and ends
Mosquito months in Bayfield County
In a normal year mosquito season in Bayfield County, WI starts around May 11 and ends around October 3, about 21 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Bayfield County, and when
- Start tipping out standing water weekly by April 27.
- Book any yard treatment for mid May, ahead of the July peak.
- Repellent can go away after October 3.
- 1 West Nile case since 2016 (last 2018): you should use repellent at dusk July, more so if over 60.
Bayfield County against the rest of WI
Bayfield County has the 64th longest season of 72 WI counties, at 145 days against 180 in La Crosse County and 139 in Rusk County. Its mean temperature is 41.2°F.
- Langlade County: May 8 to October 2 (148 days, 0 WNV)
- Price County: May 9 to October 1 (145 days, 1 WNV)
- Ashland County: May 13 to October 3 (144 days, 0 WNV)
- Iron County: May 11 to September 30 (143 days, 0 WNV)
West Nile in Bayfield County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Bayfield County (1 neuroinvasive) across 1 year. The worst was 2018 with 1; the latest was 2018.
More: how the dates are worked out · when mosquitoes go away for the winter.