Mosquito season in Eagle County, CO: when it starts and ends
Mosquito months in Eagle County
In a normal year mosquito season in Eagle County, CO starts around May 31 and ends around September 18, about 16 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Eagle County, and when
- Start tipping out standing water weekly by May 17.
- Book any yard treatment for late May, ahead of the July peak.
- Repellent can go away after September 18.
- 1 West Nile case since 2016 (last 2022): you should use repellent at dusk July, more so if over 60.
Eagle County against the rest of CO
Eagle County has the 49th longest season of 64 CO counties, at 110 days against 200 in Mesa County and 69 in Summit County. Its mean temperature is 38.6°F.
- Teller County: May 27 to September 24 (120 days, 6 WNV)
- Custer County: May 28 to September 20 (115 days, 1 WNV)
- Moffat County: June 1 to September 19 (110 days, 0 WNV)
- Garfield County: June 4 to September 20 (108 days, 2 WNV)
West Nile in Eagle County
From 1999 to 2025, CDC ArboNET counted 5 human West Nile cases in Eagle County (2 neuroinvasive) across 5 years. The worst was 2022 with 1; the latest was 2022.
More: how the dates are worked out · when mosquitoes go away for the winter.