| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 679 | 39 | 39 | 100% |
| Alpine | - | - | - | - |
| Amador | 16 | - | - | - |
| Butte | 46 | 9 | 1 | 11% |
| Calaveras | 8 | - | - | - |
| Colusa | 7 | 1 | - | - |
| Contra Costa | 402 | 66 | 13 | 20% |
| Del Norte | 4 | - | - | - |
| El Dorado | 28 | 9 | 1 | 11% |
| Fresno | 142 | 19 | 3 | 16% |
| Glenn | 2 | - | - | - |
| Humboldt | 15 | - | - | - |
| Imperial | 3 | - | - | - |
| Inyo | 2 | - | - | - |
| Kern | 28 | 3 | - | - |
| Kings | 16 | - | - | - |
| Lake | 15 | 8 | - | - |
| Lassen | 2 | - | - | - |
| Los Angeles | 1850 | 236 | 157 | 67% |
| Madera | 34 | 5 | 3 | 60% |
| Marin | 77 | 4 | - | - |
| Mariposa | 5 | - | - | - |
| Mendocino | 9 | - | - | - |
| Merced | 36 | 4 | 2 | 50% |
| Modoc | 4 | - | - | - |
| Mono | 1 | - | - | - |
| Monterey | 66 | 3 | - | - |
| Napa | 36 | 9 | 1 | 11% |
| Nevada | 27 | 4 | - | - |
| Orange | 726 | 233 | 116 | 50% |
| Placer | 225 | 96 | 9 | 9% |
| Plumas | 2 | - | - | - |
| Riverside | 241 | 54 | 13 | 24% |
| Sacramento | 937 | 399 | 107 | 27% |
| San Benito | 6 | - | - | - |
| San Bernardino | 184 | 49 | 18 | 37% |
| San Diego | 523 | 201 | 57 | 28% |
| San Francisco | 76 | 12 | - | - |
| San Joaquin | 157 | 55 | 13 | 24% |
| San Luis Obispo | 149 | 9 | - | - |
| San Mateo | 553 | 133 | 9 | 7% |
| Santa Barbara | 79 | 6 | - | - |
| Santa Clara | 935 | 284 | 115 | 40% |
| Santa Cruz | 107 | 8 | - | - |
| Shasta | 26 | 3 | - | - |
| Sierra | - | - | - | - |
| Siskiyou | 3 | - | - | - |
| Solano | 71 | 12 | 2 | 17% |
| Sonoma | 149 | 9 | 1 | 11% |
| Stanislaus | 124 | 16 | 1 | 6% |
| Sutter | 31 | 7 | 3 | 43% |
| Tehama | 5 | - | - | - |
| Trinity | 1 | - | - | - |
| Tulare | 39 | 8 | - | - |
| Tuolumne | 2 | - | - | - |
| Ventura | 126 | 29 | 7 | 24% |
| Yolo | 188 | 91 | 20 | 22% |
| Yuba | 39 | 7 | 3 | 43% |
| State Totals | 9264 | 2140 | 714 | 33% |
* 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