Mosquito season in Butte County, ID: when it starts and ends
Mosquito months in Butte County
In a normal year mosquito season in Butte County, ID starts around May 13 and ends around October 1, about 20 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Butte County, and when
- Start tipping out standing water weekly by April 29.
- Book any yard treatment for mid May, ahead of the July peak.
- Repellent can go away after October 1.
- No West Nile cases since 2016, so bites in Butte County are a nuisance; check window screens.
Butte County against the rest of ID
Butte County has the 28th longest season of 44 ID counties, at 141 days against 194 in Canyon County and 85 in Fremont County. Its mean temperature is 42.3°F.
- Lewis County: May 13 to October 4 (144 days, 1 WNV)
- Clark County: May 10 to September 30 (143 days, 0 WNV)
- Jefferson County: May 14 to September 21 (130 days, 0 WNV)
- Boise County: May 21 to September 27 (129 days, 0 WNV)
West Nile in Butte County
From 1999 to 2025, CDC ArboNET counted 5 human West Nile cases in Butte County (0 neuroinvasive) across 2 years. The worst was 2006 with 4; the latest was 2007.
Background: when the season starts across the US; how the dates are worked out.