Mosquito season in Douglas County, WA: when it starts and ends
Mosquito months in Douglas County
In a normal year mosquito season in Douglas County, WA starts around April 29 and ends around October 9, about 23 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Douglas County, and when
- Start tipping out standing water weekly by April 15.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 9.
- No West Nile cases since 2016, so bites in Douglas County are a nuisance; check window screens.
Douglas County against the rest of WA
Douglas County has the 30th longest season of 39 WA counties, at 163 days against 205 in Walla Walla County and 132 in Asotin County. Its mean temperature is 47.3°F.
- Clallam County: April 30 to October 13 (166 days, 1 WNV)
- Jefferson County: May 1 to October 13 (166 days, 0 WNV)
- Skamania County: May 3 to October 9 (159 days, 0 WNV)
- Klickitat County: May 2 to October 7 (158 days, 0 WNV)
West Nile in Douglas County
CDC ArboNET lists no human West Nile cases for Douglas County from 1999 to 2025, though virus turned up in birds, mosquitoes or horses in 1 of those years.
Background: when the season starts across the US; how the dates are worked out.