Mosquito season in Phillips County, CO: when it starts and ends
Mosquito months in Phillips County
In a normal year mosquito season in Phillips County, CO starts around May 1 and ends around October 12, about 23 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Phillips County, and when
- Start tipping out standing water weekly by April 17.
- Book any yard treatment for early May, ahead of the July peak.
- Repellent can go away after October 12.
- 3 West Nile cases since 2016 (last 2023): you should use repellent at dusk July to August, more so if over 60.
Phillips County against the rest of CO
Phillips County has the 25th longest season of 64 CO counties, at 164 days against 200 in Mesa County and 69 in Summit County. Its mean temperature is 48.9°F.
- Otero County: April 29 to October 11 (165 days, 12 WNV)
- Douglas County: May 1 to October 12 (164 days, 49 WNV)
- Lincoln County: May 1 to October 10 (162 days, 2 WNV)
- Elbert County: May 2 to October 11 (162 days, 6 WNV)
West Nile in Phillips County
From 1999 to 2025, CDC ArboNET counted 40 human West Nile cases in Phillips County (2 neuroinvasive) across 10 years. The worst was 2003 with 23; the latest was 2023.
Background: when the season starts across the US; how the dates are worked out.