Mosquito season in Fremont County, ID: when it starts and ends
Mosquito months in Fremont County
In a normal year mosquito season in Fremont County, ID starts around June 9 and ends around September 2, about 12 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Fremont County, and when
- Start tipping out standing water weekly by May 26.
- Book any yard treatment for early June, ahead of the July peak.
- Repellent can go away after September 2.
- No West Nile cases since 2016, so bites in Fremont County are a nuisance; check window screens.
Fremont County against the rest of ID
Fremont County has the 44th longest season of 44 ID counties, at 85 days against 194 in Canyon County and 85 in Fremont County. Its mean temperature is 38.5°F.
- Adams County: June 1 to September 9 (100 days, 2 WNV)
- Lemhi County: June 10 to September 4 (86 days, 2 WNV)
West Nile in Fremont County
From 1999 to 2025, CDC ArboNET counted 6 human West Nile cases in Fremont County (0 neuroinvasive) across 2 years. The worst was 2006 with 5; the latest was 2007.
See how the dates are worked out, and when mosquitoes go away for the winter.