Mosquito season in Ouray County, CO: when it starts and ends
Mosquito months in Ouray County
In a normal year mosquito season in Ouray County, CO starts around May 26 and ends around September 23, about 17 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Ouray County, and when
- Start tipping out standing water weekly by May 12.
- Book any yard treatment for late May, ahead of the July peak.
- Repellent can go away after September 23.
- No West Nile cases since 2016, so bites in Ouray County are a nuisance; check window screens.
Ouray County against the rest of CO
Ouray County has the 46th longest season of 64 CO counties, at 120 days against 200 in Mesa County and 69 in Summit County. Its mean temperature is 44.4°F.
- Pitkin County: May 23 to September 25 (126 days, 1 WNV)
- Boulder County: May 25 to September 25 (123 days, 191 WNV)
- Teller County: May 27 to September 24 (120 days, 6 WNV)
- Custer County: May 28 to September 20 (115 days, 1 WNV)
West Nile in Ouray County
CDC ArboNET lists no human West Nile cases for Ouray County from 1999 to 2025, though virus turned up in birds, mosquitoes or horses in 3 of those years.
More: how the dates are worked out · when mosquitoes go away for the winter.