Mosquito season in Ventura County, CA: when it starts and ends
Mosquito months in Ventura County
In a normal year mosquito season in Ventura County, CA starts around February 17 and ends around December 1, about 41 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Ventura County, and when
- Start tipping out standing water weekly by February 3.
- Book any yard treatment for mid February, ahead of the August peak.
- Repellent can go away after December 1.
- 13 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to August, and check CA spray notices.
Ventura County against the rest of CA
Ventura County has the 27th longest season of 58 CA counties, at 287 days against 365 in Los Angeles County and 110 in Mono County. Its mean temperature is 60.7°F.
- Tehama County: February 7 to November 30 (297 days, 15 WNV)
- Merced County: February 12 to November 27 (288 days, 60 WNV)
- Shasta County: February 20 to November 28 (280 days, 16 WNV)
- Tulare County: February 23 to November 28 (278 days, 125 WNV)
West Nile in Ventura County
From 1999 to 2025, CDC ArboNET counted 36 human West Nile cases in Ventura County (24 neuroinvasive) across 13 years. The worst was 2016 with 7; the latest was 2023.
See how the dates are worked out, and reading the West Nile counts.