Mosquito season in Custer County, ID: when it starts and ends
Mosquito months in Custer County
In a normal year mosquito season in Custer County, ID starts around June 2 and ends around September 18, about 15 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Custer County, and when
- Start tipping out standing water weekly by May 19.
- Book any yard treatment for early June, ahead of the July peak.
- Repellent can go away after September 18.
- No West Nile cases since 2016, so bites in Custer County are a nuisance; check window screens.
Custer County against the rest of ID
Custer County has the 39th longest season of 44 ID counties, at 107 days against 194 in Canyon County and 85 in Fremont County. Its mean temperature is 37.8°F.
- Elmore County: May 30 to September 18 (111 days, 4 WNV)
- Caribou County: May 27 to September 12 (108 days, 0 WNV)
- Idaho County: May 24 to September 7 (106 days, 0 WNV)
- Blaine County: June 7 to September 21 (106 days, 0 WNV)
West Nile in Custer County
From 1999 to 2025, CDC ArboNET counted 9 human West Nile cases in Custer County (0 neuroinvasive) across 3 years. The worst was 2007 with 4; the latest was 2009.
Background: when the season starts across the US; how the dates are worked out.