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

Mosquito months in Jackson County

In a normal year mosquito season in Jackson County, CO starts around June 8 and ends around September 8, about 13 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 Jackson County, and when

• Start tipping out standing water weekly by May 25.
• Book any yard treatment for early June, ahead of the July peak.
• Repellent can go away after September 8.
• No West Nile cases since 2016, so bites in Jackson County are a nuisance; check window screens.

Jackson County against the rest of CO

Jackson County has the 57th longest season of 64 CO counties, at 92 days against 200 in Mesa County and 69 in Summit County. Its mean temperature is 35.8°F.

• Hinsdale County: June 8 to September 12 (96 days, 0 WNV)
• San Miguel County: June 15 to September 16 (93 days, 2 WNV)
• Chaffee County: June 9 to September 8 (91 days, 11 WNV)
• Gilpin County: June 12 to September 7 (87 days, 0 WNV)

West Nile in Jackson County

CDC ArboNET lists no human West Nile cases for Jackson County from 1999 to 2025.

More: how the dates are worked out · when the season starts across the US.