| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 230 | 38 | - | - |
| Alpine | - | - | - | - |
| Amador | 6 | - | - | - |
| Butte | 38 | 7 | 2 | 29% |
| Calaveras | 3 | - | - | - |
| Colusa | 4 | - | - | - |
| Contra Costa | 373 | 42 | 1 | 2% |
| Del Norte | - | - | - | - |
| El Dorado | 27 | 9 | - | - |
| Fresno | 124 | 8 | 2 | 25% |
| Glenn | 4 | - | - | - |
| Humboldt | 5 | 1 | - | - |
| Imperial | - | - | - | - |
| Inyo | - | - | - | - |
| Kern | 23 | 1 | - | - |
| Kings | 11 | - | - | - |
| Lake | 12 | 6 | 2 | 33% |
| Lassen | 1 | - | - | - |
| Los Angeles | 783 | 115 | 49 | 43% |
| Madera | 8 | 3 | 2 | 67% |
| Marin | 56 | 4 | - | - |
| Mariposa | - | - | - | - |
| Mendocino | 5 | - | - | - |
| Merced | 44 | 7 | 2 | 29% |
| Modoc | - | - | - | - |
| Mono | - | - | - | - |
| Monterey | 18 | 4 | - | - |
| Napa | 20 | 9 | - | - |
| Nevada | 11 | 4 | 1 | 25% |
| Orange | 411 | 284 | 1 | 0% |
| Placer | 93 | 47 | 5 | 11% |
| Plumas | 3 | - | - | - |
| Riverside | 93 | 21 | 5 | 24% |
| Sacramento | 617 | 270 | 40 | 15% |
| San Benito | 3 | - | - | - |
| San Bernardino | 101 | 24 | 7 | 29% |
| San Diego | 127 | 47 | - | - |
| San Francisco | 44 | 8 | - | - |
| San Joaquin | 124 | 29 | 1 | 3% |
| San Luis Obispo | 16 | 2 | - | - |
| San Mateo | 262 | 64 | - | - |
| Santa Barbara | 25 | 5 | - | - |
| Santa Clara | 463 | 83 | 26 | 31% |
| Santa Cruz | 57 | 10 | - | - |
| Shasta | 28 | 6 | 1 | 17% |
| Sierra | - | - | - | - |
| Siskiyou | 1 | - | - | - |
| Solano | 143 | 33 | 9 | 27% |
| Sonoma | 98 | 19 | 1 | 5% |
| Stanislaus | 121 | 5 | - | - |
| Sutter | 47 | 13 | 4 | 31% |
| Tehama | 5 | - | - | - |
| Trinity | - | - | - | - |
| Tulare | 33 | 9 | 2 | 22% |
| Tuolumne | 3 | - | - | - |
| Ventura | 67 | 10 | 1 | 10% |
| Yolo | 177 | 73 | 24 | 33% |
| Yuba | 28 | 10 | 1 | 10% |
| State Totals | 4996 | 1330 | 189 | 14% |
* 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