Mosquito season in Silver Bow County, MT: when it starts and ends
Mosquito months in Silver Bow County
In a normal year mosquito season in Silver Bow County, MT starts around May 27 and ends around September 17, about 16 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Silver Bow County, and when
- Start tipping out standing water weekly by May 13.
- Book any yard treatment for late May, ahead of the July peak.
- Repellent can go away after September 17.
- No West Nile cases since 2016, so bites in Silver Bow County are a nuisance; check window screens.
Silver Bow County against the rest of MT
Silver Bow County has the 50th longest season of 56 MT counties, at 113 days against 163 in Dawson County and 89 in Gallatin County. Its mean temperature is 39.6°F.
- Daniels County: May 19 to September 16 (120 days, 0 WNV)
- Judith Basin County: May 25 to September 18 (116 days, 0 WNV)
- Glacier County: May 30 to September 20 (113 days, 0 WNV)
- Powell County: May 26 to September 11 (108 days, 0 WNV)
West Nile in Silver Bow County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Silver Bow County (1 neuroinvasive) across 1 year. The worst was 2013 with 1; the latest was 2013.
Background: when the season starts across the US; how the dates are worked out.