Mosquito season in Gunnison County, CO: when it starts and ends
Mosquito months in Gunnison County
In a normal year mosquito season in Gunnison County, CO starts around June 14 and ends around September 8, about 12 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Gunnison County, and when
- Start tipping out standing water weekly by May 31.
- Book any yard treatment for mid June, ahead of the July peak.
- Repellent can go away after September 8.
- 1 West Nile case since 2016 (last 2023): you should use repellent at dusk July, more so if over 60.
Gunnison County against the rest of CO
Gunnison County has the 60th longest season of 64 CO counties, at 86 days against 200 in Mesa County and 69 in Summit County. Its mean temperature is 35°F.
- Chaffee County: June 9 to September 8 (91 days, 11 WNV)
- Gilpin County: June 12 to September 7 (87 days, 0 WNV)
- Park County: June 15 to September 8 (85 days, 0 WNV)
- Lake County: June 13 to September 3 (82 days, 0 WNV)
West Nile in Gunnison County
From 1999 to 2025, CDC ArboNET counted 3 human West Nile cases in Gunnison County (1 neuroinvasive) across 3 years. The worst was 2023 with 1; the latest was 2023.
Background: when the season starts across the US; how the dates are worked out.