| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 428 | 57 | 53 | 93% |
| Alpine | - | - | - | - |
| Amador | 7 | - | - | - |
| Butte | 51 | 19 | 4 | 21% |
| Calaveras | 6 | - | - | - |
| Colusa | 2 | 1 | 1 | 100% |
| Contra Costa | 368 | 67 | 6 | 9% |
| Del Norte | 1 | - | - | - |
| El Dorado | 45 | 6 | - | - |
| Fresno | 81 | 5 | 1 | 20% |
| Glenn | 2 | - | - | - |
| Humboldt | 5 | 2 | - | - |
| Imperial | 1 | - | - | - |
| Inyo | 2 | - | - | - |
| Kern | 19 | 1 | - | - |
| Kings | 7 | - | - | - |
| Lake | 26 | 13 | 3 | 23% |
| Lassen | 3 | - | - | - |
| Los Angeles | 694 | 124 | 16 | 13% |
| Madera | 13 | 1 | 1 | 100% |
| Marin | 42 | 1 | - | - |
| Mariposa | 3 | - | - | - |
| Mendocino | 6 | - | - | - |
| Merced | 30 | 6 | 1 | 17% |
| Modoc | - | - | - | - |
| Mono | 2 | - | - | - |
| Monterey | 23 | - | - | - |
| Napa | 20 | 5 | - | - |
| Nevada | 21 | 4 | - | - |
| Orange | 246 | 58 | 1 | 2% |
| Placer | 185 | 85 | 3 | 4% |
| Plumas | 7 | - | - | - |
| Riverside | 126 | 41 | 2 | 5% |
| Sacramento | 641 | 323 | 66 | 20% |
| San Benito | 3 | - | - | - |
| San Bernardino | 117 | 36 | 10 | 28% |
| San Diego | 198 | 83 | 4 | 5% |
| San Francisco | 65 | 7 | - | - |
| San Joaquin | 126 | 31 | 6 | 19% |
| San Luis Obispo | 25 | 5 | - | - |
| San Mateo | 471 | 139 | 32 | 23% |
| Santa Barbara | 27 | 5 | - | - |
| Santa Clara | 962 | 400 | 274 | 69% |
| Santa Cruz | 56 | 9 | - | - |
| Shasta | 15 | 2 | - | - |
| Sierra | - | - | - | - |
| Siskiyou | 1 | - | - | - |
| Solano | 92 | 37 | 2 | 5% |
| Sonoma | 93 | 10 | - | - |
| Stanislaus | 93 | 9 | - | - |
| Sutter | 38 | 6 | - | - |
| Tehama | 7 | - | - | - |
| Trinity | - | - | - | - |
| Tulare | 32 | 12 | - | - |
| Tuolumne | 2 | - | - | - |
| Ventura | 75 | 15 | - | - |
| Yolo | 151 | 63 | 6 | 10% |
| Yuba | 20 | 3 | 2 | 67% |
| State Totals | 5782 | 1691 | 494 | 29% |
* 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