Mosquito season in Grays Harbor County, WA: when it starts and ends
Mosquito months in Grays Harbor County
In a normal year mosquito season in Grays Harbor County, WA starts around April 29 and ends around October 18, about 25 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Grays Harbor County, and when
- Start tipping out standing water weekly by April 15.
- Book any yard treatment for late April, ahead of the August peak.
- Repellent can go away after October 18.
- No West Nile cases since 2016, so bites in Grays Harbor County are a nuisance; check window screens.
Grays Harbor County against the rest of WA
Grays Harbor County has the 20th longest season of 39 WA counties, at 172 days against 205 in Walla Walla County and 132 in Asotin County. Its mean temperature is 49.8°F.
- Whatcom County: April 25 to October 14 (172 days, 1 WNV)
- Pierce County: April 28 to October 17 (172 days, 2 WNV)
- Skagit County: April 26 to October 14 (171 days, 0 WNV)
- Garfield County: April 25 to October 12 (169 days, 0 WNV)
West Nile in Grays Harbor County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Grays Harbor County (1 neuroinvasive) across 1 year. The worst was 2014 with 1; the latest was 2014.
More: how the dates are worked out · when the season starts across the US.