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

Mosquito months in Klamath County

In a normal year mosquito season in Klamath County, OR starts around June 10 and ends around September 13, about 14 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 Klamath County, and when

• Start tipping out standing water weekly by May 27.
• Book any yard treatment for early June, ahead of the July peak.
• Repellent can go away after September 13.
• 3 West Nile cases since 2016 (last 2023): you should use repellent at dusk July, more so if over 60.

Klamath County against the rest of OR

Klamath County has the 36th longest season of 36 OR counties, at 95 days against 225 in Curry County and 95 in Klamath County. Its mean temperature is 44.4°F.

• Malheur County: May 10 to September 27 (140 days, 19 WNV)
• Deschutes County: May 19 to October 2 (136 days, 3 WNV)

West Nile in Klamath County

From 1999 to 2025, CDC ArboNET counted 5 human West Nile cases in Klamath County (3 neuroinvasive) across 5 years. The worst was 2023 with 1; the latest was 2023.

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