| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 221 | 15 | 12 | 80% |
| Alpine | - | - | - | - |
| Amador | 1 | - | - | - |
| Butte | 21 | 7 | - | - |
| Calaveras | 3 | - | - | - |
| Colusa | - | - | - | - |
| Contra Costa | 211 | 34 | 3 | 9% |
| Del Norte | 1 | - | - | - |
| El Dorado | 33 | 5 | - | - |
| Fresno | 49 | - | - | - |
| Glenn | 1 | - | - | - |
| Humboldt | 5 | 2 | - | - |
| Imperial | 1 | - | - | - |
| Inyo | 1 | - | - | - |
| Kern | 9 | 1 | - | - |
| Kings | 5 | - | - | - |
| Lake | 11 | 5 | - | - |
| Lassen | 1 | - | - | - |
| Los Angeles | 387 | 60 | - | - |
| Madera | 8 | - | - | - |
| Marin | 29 | 1 | - | - |
| Mariposa | 1 | - | - | - |
| Mendocino | 2 | - | - | - |
| Merced | 17 | 3 | - | - |
| Modoc | - | - | - | - |
| Mono | 1 | - | - | - |
| Monterey | 16 | - | - | - |
| Napa | 13 | 2 | - | - |
| Nevada | 13 | 1 | - | - |
| Orange | 141 | 21 | - | - |
| Placer | 109 | 42 | - | - |
| Plumas | 1 | - | - | - |
| Riverside | 68 | 16 | 1 | 6% |
| Sacramento | 385 | 161 | 17 | 11% |
| San Benito | 2 | - | - | - |
| San Bernardino | 54 | 18 | 1 | 6% |
| San Diego | 126 | 54 | 2 | 4% |
| San Francisco | 27 | 2 | - | - |
| San Joaquin | 73 | 17 | 1 | 6% |
| San Luis Obispo | 18 | 3 | - | - |
| San Mateo | 205 | 58 | 5 | 9% |
| Santa Barbara | 19 | 3 | - | - |
| Santa Clara | 295 | 99 | 18 | 18% |
| Santa Cruz | 34 | 4 | - | - |
| Shasta | 11 | 1 | - | - |
| Sierra | - | - | - | - |
| Siskiyou | - | - | - | - |
| Solano | 53 | 21 | - | - |
| Sonoma | 57 | 7 | - | - |
| Stanislaus | 66 | 4 | - | - |
| Sutter | 22 | 4 | - | - |
| Tehama | 2 | - | - | - |
| Trinity | - | - | - | - |
| Tulare | 18 | 9 | - | - |
| Tuolumne | 1 | - | - | - |
| Ventura | 41 | 6 | - | - |
| Yolo | 95 | 34 | 1 | 3% |
| Yuba | 8 | - | - | - |
| State Totals | 2992 | 720 | 61 | 8% |
* 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