Mosquito season in Mariposa County, CA: when it starts and ends
Mosquito months in Mariposa County
In a normal year mosquito season in Mariposa County, CA starts around April 4 and ends around November 8, about 31 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Mariposa County, and when
- Start tipping out standing water weekly by March 21.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after November 8.
- No West Nile cases since 2016, so bites in Mariposa County are a nuisance; check window screens.
Mariposa County against the rest of CA
Mariposa County has the 45th longest season of 58 CA counties, at 217 days against 365 in Los Angeles County and 110 in Mono County. Its mean temperature is 56.1°F.
- Humboldt County: March 27 to November 7 (225 days, 1 WNV)
- Placer County: April 3 to November 10 (221 days, 35 WNV)
- Mendocino County: March 31 to October 30 (213 days, 0 WNV)
- Del Norte County: April 5 to November 2 (211 days, 0 WNV)
West Nile in Mariposa County
CDC ArboNET lists no human West Nile cases for Mariposa County from 1999 to 2025, though virus turned up in birds, mosquitoes or horses in 3 of those years.
See how the dates are worked out, and when mosquitoes go away for the winter.