| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 221 | 16 | - | - |
| Alpine | - | - | - | - |
| Amador | 6 | - | - | - |
| Butte | 38 | 7 | 2 | 29% |
| Calaveras | 3 | - | - | - |
| Colusa | 4 | - | - | - |
| Contra Costa | 362 | 38 | 1 | 3% |
| Del Norte | - | - | - | - |
| El Dorado | 27 | 9 | - | - |
| Fresno | 123 | 7 | 2 | 29% |
| Glenn | 4 | - | - | - |
| Humboldt | 5 | 1 | - | - |
| Imperial | - | - | - | - |
| Inyo | - | - | - | - |
| Kern | 22 | - | - | - |
| Kings | 10 | - | - | - |
| Lake | 12 | 5 | 2 | 40% |
| Lassen | 1 | - | - | - |
| Los Angeles | 771 | 113 | 47 | 42% |
| Madera | 8 | 3 | 2 | 67% |
| Marin | 55 | 4 | - | - |
| Mariposa | - | - | - | - |
| Mendocino | 5 | - | - | - |
| Merced | 44 | 6 | 1 | 17% |
| Modoc | - | - | - | - |
| Mono | - | - | - | - |
| Monterey | 17 | 4 | - | - |
| Napa | 19 | 9 | - | - |
| Nevada | 11 | 3 | 1 | 33% |
| Orange | 390 | 279 | 1 | 0% |
| Placer | 90 | 47 | 5 | 11% |
| Plumas | 3 | - | - | - |
| Riverside | 89 | 21 | 5 | 24% |
| Sacramento | 604 | 269 | 40 | 15% |
| San Benito | 3 | - | - | - |
| San Bernardino | 101 | 24 | 7 | 29% |
| San Diego | 118 | 42 | - | - |
| San Francisco | 42 | 8 | - | - |
| San Joaquin | 123 | 29 | 1 | 3% |
| San Luis Obispo | 15 | 2 | - | - |
| San Mateo | 246 | 59 | - | - |
| Santa Barbara | 24 | 4 | - | - |
| Santa Clara | 456 | 81 | 26 | 32% |
| Santa Cruz | 54 | 10 | - | - |
| Shasta | 27 | 5 | 1 | 20% |
| Sierra | - | - | - | - |
| Siskiyou | 1 | - | - | - |
| Solano | 140 | 33 | 9 | 27% |
| Sonoma | 95 | 19 | 1 | 5% |
| Stanislaus | 119 | 5 | - | - |
| Sutter | 42 | 13 | 4 | 31% |
| Tehama | 5 | - | - | - |
| Trinity | - | - | - | - |
| Tulare | 33 | 7 | 2 | 29% |
| Tuolumne | 3 | - | - | - |
| Ventura | 66 | 10 | 1 | 10% |
| Yolo | 171 | 73 | 24 | 33% |
| Yuba | 28 | 10 | 1 | 10% |
| State Totals | 4856 | 1275 | 186 | 15% |
* 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