| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 378 | 117 | 8 | 7% |
| Alpine | 2 | 2 | 1 | 50% |
| Amador | 4 | - | - | - |
| Butte | 48 | 12 | 4 | 33% |
| Calaveras | 1 | - | - | - |
| Colusa | 1 | - | - | - |
| Contra Costa | 501 | 61 | 22 | 36% |
| Del Norte | - | - | - | - |
| El Dorado | 31 | 13 | - | - |
| Fresno | 194 | 16 | 5 | 31% |
| Glenn | 1 | - | - | - |
| Humboldt | 7 | 2 | - | - |
| Imperial | 1 | - | - | - |
| Inyo | - | - | - | - |
| Kern | 9 | 1 | - | - |
| Kings | 9 | - | - | - |
| Lake | 12 | 7 | - | - |
| Lassen | - | - | - | - |
| Los Angeles | 863 | 200 | 102 | 51% |
| Madera | 16 | - | - | - |
| Marin | 32 | 3 | 1 | 33% |
| Mariposa | - | - | - | - |
| Mendocino | 2 | - | - | - |
| Merced | 73 | 5 | 2 | 40% |
| Modoc | - | - | - | - |
| Mono | 1 | - | - | - |
| Monterey | 19 | 4 | - | - |
| Napa | 13 | 3 | 1 | 33% |
| Nevada | 24 | 2 | - | - |
| Orange | 553 | 229 | 47 | 21% |
| Placer | 138 | 57 | 3 | 5% |
| Plumas | 2 | - | - | - |
| Riverside | 150 | 31 | 2 | 6% |
| Sacramento | 709 | 317 | 91 | 29% |
| San Benito | 2 | - | - | - |
| San Bernardino | 67 | 11 | - | - |
| San Diego | 197 | 115 | 1 | 1% |
| San Francisco | 51 | 6 | - | - |
| San Joaquin | 159 | 38 | 4 | 11% |
| San Luis Obispo | 16 | 2 | - | - |
| San Mateo | 244 | 85 | 1 | 1% |
| Santa Barbara | 23 | 4 | - | - |
| Santa Clara | 486 | 152 | 7 | 5% |
| Santa Cruz | 79 | 18 | - | - |
| Shasta | 20 | 1 | - | - |
| Sierra | - | - | - | - |
| Siskiyou | - | - | - | - |
| Solano | 83 | 28 | 3 | 11% |
| Sonoma | 62 | 7 | - | - |
| Stanislaus | 178 | 12 | 4 | 33% |
| Sutter | 37 | 11 | - | - |
| Tehama | 5 | - | - | - |
| Trinity | - | - | - | - |
| Tulare | 54 | 12 | 5 | 42% |
| Tuolumne | 1 | 1 | - | - |
| Ventura | 61 | 18 | - | - |
| Yolo | 211 | 88 | 29 | 33% |
| Yuba | 25 | 1 | - | - |
| State Totals | 5855 | 1692 | 343 | 20% |
* 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