Mosquito season in Kern County, CA: when it starts and ends
Mosquito months in Kern County
In a normal year mosquito season in Kern County, CA starts around January 25 and ends around December 8, about 45 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Kern County, and when
- Start tipping out standing water weekly by January 11.
- Book any yard treatment for late January, ahead of the July peak.
- Repellent can go away after December 8.
- 173 West Nile cases since 2016: you should wear EPA-registered repellent at dusk June to September, and check CA spray notices.
Kern County against the rest of CA
Kern County has the 11th longest season of 58 CA counties, at 316 days against 365 in Los Angeles County and 110 in Mono County. Its mean temperature is 65°F.
- Fresno County: January 22 to December 10 (321 days, 201 WNV)
- Marin County: January 24 to December 10 (321 days, 0 WNV)
- San Joaquin County: January 27 to December 7 (314 days, 86 WNV)
- Solano County: January 28 to December 7 (313 days, 18 WNV)
West Nile in Kern County
From 1999 to 2025, CDC ArboNET counted 614 human West Nile cases in Kern County (290 neuroinvasive) across 22 years. The worst was 2007 with 140; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.