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

Mosquito months in Sherman County

In a normal year mosquito season in Sherman County, OR starts around April 28 and ends around October 14, about 24 weeks.

1. Jan
2. Feb
3. Mar
4. Apr
5. May
6. Jun
7. Jul
8. Aug
9. Sep
10. Oct
11. Nov
12. Dec

What to do in Sherman County, and when

• Start tipping out standing water weekly by April 14.
• Book any yard treatment for late April, ahead of the July peak.
• Repellent can go away after October 14.
• No West Nile cases since 2016, so bites in Sherman County are a nuisance; check window screens.

Sherman County against the rest of OR

Sherman County has the 23rd longest season of 36 OR counties, at 169 days against 225 in Curry County and 95 in Klamath County. Its mean temperature is 49.1°F.

• Gilliam County: April 26 to October 14 (171 days, 0 WNV)
• Union County: April 26 to October 12 (169 days, 0 WNV)
• Jefferson County: May 2 to October 12 (163 days, 1 WNV)
• Wheeler County: May 6 to October 11 (158 days, 0 WNV)

West Nile in Sherman County

CDC ArboNET lists no human West Nile cases for Sherman County from 1999 to 2025.

More: how the dates are worked out · when the season starts across the US.