| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 510 | 32 | 32 | 100% |
| Alpine | - | - | - | - |
| Amador | 12 | - | - | - |
| Butte | 34 | 4 | - | - |
| Calaveras | 7 | - | - | - |
| Colusa | 5 | - | - | - |
| Contra Costa | 274 | 33 | 7 | 21% |
| Del Norte | 2 | - | - | - |
| El Dorado | 17 | 4 | - | - |
| Fresno | 113 | 15 | 3 | 20% |
| Glenn | 1 | - | - | - |
| Humboldt | 14 | - | - | - |
| Imperial | 1 | - | - | - |
| Inyo | 2 | - | - | - |
| Kern | 22 | 3 | - | - |
| Kings | 12 | - | - | - |
| Lake | 10 | 4 | - | - |
| Lassen | 2 | - | - | - |
| Los Angeles | 1113 | 125 | 60 | 48% |
| Madera | 24 | 4 | 2 | 50% |
| Marin | 46 | 2 | - | - |
| Mariposa | 4 | - | - | - |
| Mendocino | 5 | - | - | - |
| Merced | 23 | 1 | - | - |
| Modoc | 4 | - | - | - |
| Mono | 1 | - | - | - |
| Monterey | 49 | 3 | - | - |
| Napa | 28 | 5 | 1 | 20% |
| Nevada | 22 | 4 | - | - |
| Orange | 381 | 65 | 2 | 3% |
| Placer | 170 | 68 | 4 | 6% |
| Plumas | 2 | - | - | - |
| Riverside | 156 | 28 | 1 | 4% |
| Sacramento | 722 | 295 | 85 | 29% |
| San Benito | 3 | - | - | - |
| San Bernardino | 120 | 30 | 8 | 27% |
| San Diego | 395 | 138 | 26 | 19% |
| San Francisco | 63 | 8 | - | - |
| San Joaquin | 107 | 32 | 4 | 13% |
| San Luis Obispo | 95 | 8 | - | - |
| San Mateo | 443 | 113 | 9 | 8% |
| Santa Barbara | 66 | 4 | - | - |
| Santa Clara | 739 | 219 | 74 | 34% |
| Santa Cruz | 73 | 4 | - | - |
| Shasta | 17 | 2 | - | - |
| Sierra | - | - | - | - |
| Siskiyou | 1 | - | - | - |
| Solano | 47 | 9 | 2 | 22% |
| Sonoma | 113 | 6 | - | - |
| Stanislaus | 87 | 11 | - | - |
| Sutter | 22 | 4 | 2 | 50% |
| Tehama | 5 | - | - | - |
| Trinity | 1 | - | - | - |
| Tulare | 26 | 6 | - | - |
| Tuolumne | 2 | - | - | - |
| Ventura | 90 | 18 | 3 | 17% |
| Yolo | 129 | 49 | 9 | 18% |
| Yuba | 31 | 6 | 2 | 33% |
| State Totals | 6463 | 1362 | 336 | 25% |
* Birds in a die-off are not included in reported totals because the deaths are not related to WNV. A die-off is defined as a group of 10 or more same species dead birds unless the species is American Crow.
Source: Vector-Borne Disease Section, California Department of Public Health