Mosquito season in Clear Creek County, CO: when it starts and ends

Mosquito months in Clear Creek County

In a normal year mosquito season in Clear Creek County, CO starts around June 7 and ends around September 14, about 14 weeks.

1. Jan
2. Feb
3. Mar
4. Apr
5. May
6. Jun
7. Jul
8. Aug
9. Sep
10. Oct
11. Nov
12. Dec

What to do in Clear Creek County, and when

• Start tipping out standing water weekly by May 24.
• Book any yard treatment for early June, ahead of the July peak.
• Repellent can go away after September 14.
• 2 West Nile cases since 2016 (last 2021): you should use repellent at dusk July, more so if over 60.

Clear Creek County against the rest of CO

Clear Creek County has the 53rd longest season of 64 CO counties, at 99 days against 200 in Mesa County and 69 in Summit County. Its mean temperature is 37.8°F.

• Garfield County: June 4 to September 20 (108 days, 2 WNV)
• Grand County: June 4 to September 15 (102 days, 3 WNV)
• Mineral County: June 10 to September 16 (98 days, 0 WNV)
• Hinsdale County: June 8 to September 12 (96 days, 0 WNV)

West Nile in Clear Creek County

From 1999 to 2025, CDC ArboNET counted 3 human West Nile cases in Clear Creek County (2 neuroinvasive) across 3 years. The worst was 2021 with 1; the latest was 2021.

Background: when mosquitoes go away for the winter; how the dates are worked out.