Mosquito season in Santa Barbara County, CA: when it starts and ends

Mosquito months in Santa Barbara County

In a normal year mosquito season in Santa Barbara County, CA starts around February 27 and ends around November 27, about 39 weeks.

1. Jan
2. Feb
3. Mar
4. Apr
5. May
6. Jun
7. Jul
8. Aug
9. Sep
10. Oct
11. Nov
12. Dec

What to do in Santa Barbara County, and when

• Start tipping out standing water weekly by February 13.
• Book any yard treatment for late February, ahead of the August peak.
• Repellent can go away after November 27.
• 2 West Nile cases since 2016 (last 2021): you should use repellent at dusk July to September, more so if over 60.

Santa Barbara County against the rest of CA

Santa Barbara County has the 32nd longest season of 58 CA counties, at 273 days against 365 in Los Angeles County and 110 in Mono County. Its mean temperature is 60.3°F.

• Napa County: February 24 to November 27 (276 days, 1 WNV)
• Yuba County: February 27 to November 28 (274 days, 24 WNV)
• San Luis Obispo County: February 22 to November 21 (272 days, 6 WNV)
• Calaveras County: March 4 to November 26 (267 days, 2 WNV)

West Nile in Santa Barbara County

From 1999 to 2025, CDC ArboNET counted 7 human West Nile cases in Santa Barbara County (5 neuroinvasive) across 5 years. The worst was 2021 with 2; the latest was 2021.

Background: when the season starts across the US; how the dates are worked out.