Mosquito season in Archuleta County, CO: when it starts and ends
Mosquito months in Archuleta County
In a normal year mosquito season in Archuleta County, CO starts around May 23 and ends around September 30, about 19 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Archuleta County, and when
- Start tipping out standing water weekly by May 9.
- Book any yard treatment for late May, ahead of the July peak.
- Repellent can go away after September 30.
- 4 West Nile cases since 2016 (last 2023): you should use repellent at dusk July, more so if over 60.
Archuleta County against the rest of CO
Archuleta County has the 41st longest season of 64 CO counties, at 130 days against 200 in Mesa County and 69 in Summit County. Its mean temperature is 45.9°F.
- Alamosa County: May 16 to September 27 (134 days, 2 WNV)
- Rio Grande County: May 19 to September 26 (130 days, 1 WNV)
- Routt County: May 20 to September 23 (126 days, 0 WNV)
- Larimer County: May 23 to September 26 (126 days, 225 WNV)
West Nile in Archuleta County
From 1999 to 2025, CDC ArboNET counted 7 human West Nile cases in Archuleta County (3 neuroinvasive) across 5 years. The worst was 2023 with 2; the latest was 2023.
See how the dates are worked out, and reading the West Nile counts.