| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 515 | 187 | 53 | 28% |
| Alpine | - | - | - | - |
| Amador | 7 | - | - | - |
| Butte | 56 | 19 | 4 | 21% |
| Calaveras | 7 | - | - | - |
| Colusa | 3 | 1 | 1 | 100% |
| Contra Costa | 439 | 67 | 6 | 9% |
| Del Norte | 2 | - | - | - |
| El Dorado | 54 | 6 | - | - |
| Fresno | 91 | 6 | 2 | 33% |
| Glenn | 4 | - | - | - |
| Humboldt | 7 | 2 | - | - |
| Imperial | 1 | - | - | - |
| Inyo | 2 | - | - | - |
| Kern | 22 | 1 | - | - |
| Kings | 9 | - | - | - |
| Lake | 28 | 14 | 3 | 21% |
| Lassen | 3 | - | - | - |
| Los Angeles | 800 | 126 | 17 | 13% |
| Madera | 14 | 1 | 1 | 100% |
| Marin | 53 | 1 | - | - |
| Mariposa | 4 | - | - | - |
| Mendocino | 9 | - | - | - |
| Merced | 40 | 6 | 1 | 17% |
| Modoc | - | - | - | - |
| Mono | 2 | - | - | - |
| Monterey | 30 | - | - | - |
| Napa | 22 | 5 | - | - |
| Nevada | 23 | 4 | - | - |
| Orange | 276 | 62 | 1 | 2% |
| Placer | 208 | 91 | 4 | 4% |
| Plumas | 7 | - | - | - |
| Riverside | 145 | 45 | 4 | 9% |
| Sacramento | 737 | 325 | 66 | 20% |
| San Benito | 4 | - | - | - |
| San Bernardino | 133 | 37 | 10 | 27% |
| San Diego | 246 | 108 | 8 | 7% |
| San Francisco | 80 | 8 | - | - |
| San Joaquin | 137 | 31 | 6 | 19% |
| San Luis Obispo | 29 | 5 | - | - |
| San Mateo | 550 | 160 | 37 | 23% |
| Santa Barbara | 29 | 5 | - | - |
| Santa Clara | 1077 | 436 | 301 | 69% |
| Santa Cruz | 70 | 9 | - | - |
| Shasta | 20 | 2 | - | - |
| Sierra | - | - | - | - |
| Siskiyou | 2 | - | - | - |
| Solano | 113 | 38 | 2 | 5% |
| Sonoma | 117 | 10 | - | - |
| Stanislaus | 102 | 10 | - | - |
| Sutter | 42 | 6 | - | - |
| Tehama | 8 | - | - | - |
| Trinity | - | - | - | - |
| Tulare | 38 | 13 | 1 | 8% |
| Tuolumne | 2 | - | - | - |
| Ventura | 81 | 15 | - | - |
| Yolo | 179 | 66 | 6 | 9% |
| Yuba | 23 | 3 | 2 | 67% |
| State Totals | 6702 | 1931 | 536 | 28% |
* 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