Mosquito season in Deschutes County, OR: when it starts and ends
Mosquito months in Deschutes County
In a normal year mosquito season in Deschutes County, OR starts around May 19 and ends around October 2, about 19 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Deschutes County, and when
- Start tipping out standing water weekly by May 5.
- Book any yard treatment for mid May, ahead of the July peak.
- Repellent can go away after October 2.
- 3 West Nile cases since 2016 (last 2025): you should use repellent at dusk July, more so if over 60.
Deschutes County against the rest of OR
Deschutes County has the 35th longest season of 36 OR counties, at 136 days against 225 in Curry County and 95 in Klamath County. Its mean temperature is 44.8°F.
- Grant County: May 13 to October 1 (141 days, 1 WNV)
- Malheur County: May 10 to September 27 (140 days, 19 WNV)
- Klamath County: June 10 to September 13 (95 days, 3 WNV)
West Nile in Deschutes County
From 1999 to 2025, CDC ArboNET counted 5 human West Nile cases in Deschutes County (3 neuroinvasive) across 5 years. The worst was 2025 with 1; the latest was 2025.
Background: when the season starts across the US; how the dates are worked out.