Mosquito season in Toole County, MT: when it starts and ends
Mosquito months in Toole County
In a normal year mosquito season in Toole County, MT starts around May 11 and ends around September 26, about 20 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Toole County, and when
- Start tipping out standing water weekly by April 27.
- Book any yard treatment for mid May, ahead of the July peak.
- Repellent can go away after September 26.
- 4 West Nile cases since 2016 (last 2018): you should use repellent at dusk July, more so if over 60.
Toole County against the rest of MT
Toole County has the 30th longest season of 56 MT counties, at 138 days against 163 in Dawson County and 89 in Gallatin County. Its mean temperature is 42°F.
- Teton County: May 14 to September 29 (139 days, 1 WNV)
- Liberty County: May 11 to September 26 (138 days, 0 WNV)
- Powder River County: May 14 to September 29 (138 days, 1 WNV)
- Custer County: May 11 to September 25 (137 days, 6 WNV)
West Nile in Toole County
From 1999 to 2025, CDC ArboNET counted 7 human West Nile cases in Toole County (3 neuroinvasive) across 4 years. The worst was 2018 with 3; the latest was 2018.
Background: reading the West Nile counts; how the dates are worked out.