Mosquito season in Bonneville County, ID: when it starts and ends
Mosquito months in Bonneville County
In a normal year mosquito season in Bonneville County, ID starts around May 19 and ends around September 23, about 18 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Bonneville County, and when
- Start tipping out standing water weekly by May 5.
- Book any yard treatment for mid May, ahead of the July peak.
- Repellent can go away after September 23.
- No West Nile cases since 2016, so bites in Bonneville County are a nuisance; check window screens.
Bonneville County against the rest of ID
Bonneville County has the 31st longest season of 44 ID counties, at 127 days against 194 in Canyon County and 85 in Fremont County. Its mean temperature is 42.6°F.
- Jefferson County: May 14 to September 21 (130 days, 0 WNV)
- Boise County: May 21 to September 27 (129 days, 0 WNV)
- Clearwater County: May 18 to September 20 (125 days, 0 WNV)
- Teton County: May 22 to September 20 (121 days, 1 WNV)
West Nile in Bonneville County
From 1999 to 2025, CDC ArboNET counted 39 human West Nile cases in Bonneville County (3 neuroinvasive) across 4 years. The worst was 2006 with 32; the latest was 2009.
More: how the dates are worked out · when the season starts across the US.