Mosquito season in Plumas County, CA: when it starts and ends
Mosquito months in Plumas County
In a normal year mosquito season in Plumas County, CA starts around May 17 and ends around October 1, about 20 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Plumas County, and when
- Start tipping out standing water weekly by May 3.
- Book any yard treatment for mid May, ahead of the July peak.
- Repellent can go away after October 1.
- No West Nile cases since 2016, so bites in Plumas County are a nuisance; check window screens.
Plumas County against the rest of CA
Plumas County has the 54th longest season of 58 CA counties, at 137 days against 365 in Los Angeles County and 110 in Mono County. Its mean temperature is 48.6°F.
- Nevada County: May 8 to October 25 (171 days, 3 WNV)
- Modoc County: May 11 to September 25 (137 days, 0 WNV)
- Sierra County: May 24 to October 5 (133 days, 0 WNV)
- Alpine County: May 28 to October 3 (128 days, 0 WNV)
West Nile in Plumas County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Plumas County (1 neuroinvasive) across 1 year. The worst was 2005 with 1; the latest was 2005.
See how the dates are worked out, and when mosquitoes go away for the winter.