California mosquito forecast, by town

A daily mosquito bite-risk score for all 1091 California towns, grouped by their 57 counties. Mosquito pressure is local, so pick your town for today's number, a 7-day outlook, and what's driving it.

Alameda County · 19 towns

Amador County · 11 towns

Butte County · 14 towns

Calaveras County · 8 towns

Colusa County · 4 towns

Contra Costa County · 49 towns

Del Norte County · 3 towns

El Dorado County · 13 towns

Fresno County · 29 towns

Glenn County · 3 towns

Humboldt County · 18 towns

Imperial County · 11 towns

Inyo County · 5 towns

Kern County · 52 towns

Kings County · 9 towns

Lake County · 14 towns

Lassen County · 3 towns

Los Angeles County · 141 towns

Madera County · 13 towns

Marin County · 23 towns

Mariposa County · 2 towns

Mendocino County · 9 towns

Merced County · 15 towns

Modoc County · 1 towns

Mono County · 1 towns

Monterey County · 23 towns

Napa County · 7 towns

Nevada County · 7 towns

Orange County · 42 towns

Placer County · 17 towns

Plumas County · 5 towns

Riverside County · 68 towns

Sacramento County · 30 towns

San Benito County · 3 towns

San Bernardino County · 47 towns

San Diego County · 51 towns

San Francisco County · 1 towns

San Joaquin County · 22 towns

San Luis Obispo County · 23 towns

San Mateo County · 30 towns

Santa Barbara County · 22 towns

Santa Clara County · 23 towns

Santa Cruz County · 26 towns

Shasta County · 12 towns

Sierra County · 1 towns

Siskiyou County · 10 towns

Solano County · 10 towns

Sonoma County · 23 towns

Stanislaus County · 25 towns

Sutter County · 3 towns

Tehama County · 7 towns

Trinity County · 4 towns

Tulare County · 26 towns

Tuolumne County · 11 towns

Ventura County · 24 towns

Yolo County · 10 towns

Yuba County · 8 towns

California mosquito questions

What kinds of mosquitoes live in California?
California has floodwater mosquitoes (the dominant summer nuisance biter, which surges after heavy rain), the Asian tiger mosquito (a daytime biter that breeds in yard containers), the house mosquito (the main West Nile carrier), and swamp and cattail-marsh mosquitoes tied to the EEE cycle. Which ones dominate a given town depends on its local breeding habitat.
When does mosquito season start and end in California?
In California, mosquito numbers build from about mid-June, peak in mid-to-late summer, and fade with the first cool nights of fall. Biting largely stops once temperatures drop below about 50°F, and a hard freeze ends the season.
Is West Nile or EEE a risk in California?
Both West Nile virus and Eastern equine encephalitis occur in the region, but human cases are rare. West Nile risk peaks in late-summer heat and tracks the house mosquito in developed areas; EEE rises after mid-July in swampy areas. For confirmed local activity, check the California health department's arbovirus surveillance.
How do I keep mosquitoes out of my yard in California?
The single biggest thing you control is standing water: empty anything that holds it, keep gutters clear, and change bird baths weekly. Use EPA-registered repellent at dawn and dusk, and for heavy biting a licensed mosquito-control service can treat breeding sites and resting spots you can't reach.