Mosquito season in Park County, WY: when it starts and ends
Mosquito months in Park County
In a normal year mosquito season in Park County, WY starts around June 4 and ends around September 17, about 15 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Park County, and when
- Start tipping out standing water weekly by May 21.
- Book any yard treatment for early June, ahead of the July peak.
- Repellent can go away after September 17.
- 3 West Nile cases since 2016 (last 2025): you should use repellent at dusk July, more so if over 60.
Park County against the rest of WY
Park County has the 20th longest season of 23 WY counties, at 105 days against 163 in Big Horn County and 75 in Teton County. Its mean temperature is 38.4°F.
- Albany County: May 22 to September 14 (115 days, 1 WNV)
- Uinta County: May 30 to September 20 (113 days, 1 WNV)
- Lincoln County: June 8 to September 11 (95 days, 0 WNV)
- Sublette County: June 6 to September 4 (90 days, 0 WNV)
West Nile in Park County
From 1999 to 2025, CDC ArboNET counted 15 human West Nile cases in Park County (9 neuroinvasive) across 7 years. The worst was 2003 with 5; the latest was 2025.
See how the dates are worked out, and when mosquitoes go away for the winter.