Mosquito season in Crook County, OR: when it starts and ends

Mosquito months in Crook County

In a normal year mosquito season in Crook County, OR starts around May 12 and ends around September 30, about 20 weeks.

What to do in Crook County, and when

Start tipping out standing water weekly by April 28.
Book any yard treatment for mid May, ahead of the July peak.
Repellent can go away after September 30.
No West Nile cases since 2016, so bites in Crook County are a nuisance; check window screens.

Crook County against the rest of OR

Crook County has the 32nd longest season of 36 OR counties, at 141 days against 225 in Curry County and 95 in Klamath County. Its mean temperature is 48°F.

Baker County: May 8 to September 27 (142 days, 8 WNV)
Lake County: May 10 to September 28 (141 days, 0 WNV)
Grant County: May 13 to October 1 (141 days, 1 WNV)
Malheur County: May 10 to September 27 (140 days, 19 WNV)

West Nile in Crook County

CDC ArboNET lists no human West Nile cases for Crook County from 1999 to 2025, though virus turned up in birds, mosquitoes or horses in 1 of those years.

See how the dates are worked out, and when the season starts across the US.