| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 276 | 39 | 2 | 5% |
| Alpine | 1 | - | - | - |
| Amador | 11 | - | - | - |
| Butte | 98 | 24 | 5 | 21% |
| Calaveras | 8 | - | - | - |
| Colusa | 10 | 2 | 1 | 50% |
| Contra Costa | 695 | 43 | 19 | 44% |
| Del Norte | - | - | - | - |
| El Dorado | 72 | 18 | 2 | 11% |
| Fresno | 168 | 11 | 5 | 45% |
| Glenn | 6 | 2 | 2 | 100% |
| Humboldt | 12 | 2 | 1 | 50% |
| Imperial | 3 | - | - | - |
| Inyo | 12 | - | - | - |
| Kern | 76 | 3 | 3 | 100% |
| Kings | 28 | 3 | 1 | 33% |
| Lake | 40 | 25 | 5 | 20% |
| Lassen | - | - | - | - |
| Los Angeles | 889 | 160 | 101 | 63% |
| Madera | 27 | 3 | 1 | 33% |
| Marin | 64 | 9 | 1 | 11% |
| Mariposa | 4 | - | - | - |
| Mendocino | 11 | - | - | - |
| Merced | 64 | 7 | 1 | 14% |
| Modoc | - | - | - | - |
| Mono | 2 | - | - | - |
| Monterey | 34 | 4 | 1 | 25% |
| Napa | 39 | 5 | - | - |
| Nevada | 25 | 8 | 1 | 13% |
| Orange | 674 | 475 | 57 | 12% |
| Placer | 250 | 124 | 4 | 3% |
| Plumas | 1 | - | - | - |
| Riverside | 289 | 68 | 41 | 60% |
| Sacramento | 945 | 358 | 86 | 24% |
| San Benito | 9 | 1 | - | - |
| San Bernardino | 258 | 59 | 45 | 76% |
| San Diego | 246 | 107 | 44 | 41% |
| San Francisco | 55 | 11 | 1 | 9% |
| San Joaquin | 233 | 40 | 7 | 18% |
| San Luis Obispo | 59 | 13 | 6 | 46% |
| San Mateo | 404 | 79 | 1 | 1% |
| Santa Barbara | 37 | 6 | 1 | 17% |
| Santa Clara | 515 | 103 | 15 | 15% |
| Santa Cruz | 80 | 18 | 1 | 6% |
| Shasta | 47 | 3 | 2 | 67% |
| Sierra | 1 | - | - | - |
| Siskiyou | 1 | - | - | - |
| Solano | 104 | 21 | 4 | 19% |
| Sonoma | 130 | 26 | 5 | 19% |
| Stanislaus | 217 | 22 | 6 | 27% |
| Sutter | 58 | 22 | 3 | 14% |
| Tehama | 9 | - | - | - |
| Trinity | 1 | 1 | - | - |
| Tulare | 82 | 16 | 8 | 50% |
| Tuolumne | 7 | 1 | - | - |
| Ventura | 119 | 16 | 2 | 13% |
| Yolo | 195 | 61 | 14 | 23% |
| Yuba | 44 | 16 | 6 | 38% |
| State Totals | 7745 | 2035 | 511 | 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