Mosquito season in Benton County, OR: when it starts and ends
Mosquito months in Benton County
In a normal year mosquito season in Benton County, OR starts around April 27 and ends around October 18, about 25 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Benton County, and when
- Start tipping out standing water weekly by April 13.
- Book any yard treatment for late April, ahead of the August peak.
- Repellent can go away after October 18.
- 2 West Nile cases since 2016 (last 2023): you should use repellent at dusk August, more so if over 60.
Benton County against the rest of OR
Benton County has the 19th longest season of 36 OR counties, at 174 days against 225 in Curry County and 95 in Klamath County. Its mean temperature is 50.1°F.
- Columbia County: April 25 to October 18 (175 days, 1 WNV)
- Tillamook County: May 3 to October 25 (175 days, 0 WNV)
- Clackamas County: April 29 to October 17 (172 days, 1 WNV)
- Gilliam County: April 26 to October 14 (171 days, 0 WNV)
West Nile in Benton County
From 1999 to 2025, CDC ArboNET counted 4 human West Nile cases in Benton County (2 neuroinvasive) across 3 years. The worst was 2023 with 2; the latest was 2023.
See how the dates are worked out, and when the season starts across the US.