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

Mosquito months in Las Animas County

In a normal year mosquito season in Las Animas County, CO starts around April 23 and ends around October 18, about 25 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 Las Animas County, and when

• Start tipping out standing water weekly by April 9.
• Book any yard treatment for late April, ahead of the July peak.
• Repellent can go away after October 18.
• 2 West Nile cases since 2016 (last 2023): you should use repellent at dusk July to August, more so if over 60.

Las Animas County against the rest of CO

Las Animas County has the 9th longest season of 64 CO counties, at 178 days against 200 in Mesa County and 69 in Summit County. Its mean temperature is 52.7°F.

• Logan County: April 19 to October 17 (181 days, 19 WNV)
• Denver County: April 22 to October 18 (179 days, 189 WNV)
• Baca County: April 24 to October 19 (178 days, 3 WNV)
• Crowley County: April 23 to October 16 (176 days, 2 WNV)

West Nile in Las Animas County

From 1999 to 2025, CDC ArboNET counted 13 human West Nile cases in Las Animas County (6 neuroinvasive) across 5 years. The worst was 2003 with 7; the latest was 2023.

See how the dates are worked out, and when mosquitoes go away for the winter.