Mosquito season in Park County, MT: when it starts and ends
Mosquito months in Park County
In a normal year mosquito season in Park County, MT starts around May 14 and ends around October 1, about 20 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 April 30.
- Book any yard treatment for mid May, ahead of the July peak.
- Repellent can go away after October 1.
- 1 West Nile case since 2016 (last 2023): you should use repellent at dusk July, more so if over 60.
Park County against the rest of MT
Park County has the 27th longest season of 56 MT counties, at 140 days against 163 in Dawson County and 89 in Gallatin County. Its mean temperature is 44.1°F.
- Big Horn County: May 10 to September 28 (141 days, 4 WNV)
- Mineral County: May 12 to September 30 (141 days, 0 WNV)
- Teton County: May 14 to September 29 (139 days, 1 WNV)
- Liberty County: May 11 to September 26 (138 days, 0 WNV)
West Nile in Park County
From 1999 to 2025, CDC ArboNET counted 3 human West Nile cases in Park County (2 neuroinvasive) across 3 years. The worst was 2023 with 1; the latest was 2023.
See how the dates are worked out, and when the season starts across the US.