| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 657 | 38 | 38 | 100% |
| Alpine | - | - | - | - |
| Amador | 15 | - | - | - |
| Butte | 44 | 6 | - | - |
| Calaveras | 8 | - | - | - |
| Colusa | 7 | 1 | - | - |
| Contra Costa | 375 | 63 | 11 | 17% |
| Del Norte | 4 | - | - | - |
| El Dorado | 28 | 8 | 1 | 13% |
| Fresno | 138 | 19 | 3 | 16% |
| Glenn | 1 | - | - | - |
| Humboldt | 15 | - | - | - |
| Imperial | 2 | - | - | - |
| Inyo | 2 | - | - | - |
| Kern | 26 | 3 | - | - |
| Kings | 15 | - | - | - |
| Lake | 13 | 6 | - | - |
| Lassen | 2 | - | - | - |
| Los Angeles | 1716 | 220 | 148 | 67% |
| Madera | 33 | 5 | 3 | 60% |
| Marin | 69 | 4 | - | - |
| Mariposa | 5 | - | - | - |
| Mendocino | 8 | - | - | - |
| Merced | 35 | 3 | 2 | 67% |
| Modoc | 4 | - | - | - |
| Mono | 1 | - | - | - |
| Monterey | 61 | 3 | - | - |
| Napa | 36 | 9 | 1 | 11% |
| Nevada | 26 | 4 | - | - |
| Orange | 646 | 197 | 94 | 48% |
| Placer | 215 | 90 | 9 | 10% |
| Plumas | 2 | - | - | - |
| Riverside | 228 | 48 | 10 | 21% |
| Sacramento | 882 | 376 | 106 | 28% |
| San Benito | 6 | - | - | - |
| San Bernardino | 169 | 45 | 18 | 40% |
| San Diego | 489 | 186 | 47 | 25% |
| San Francisco | 76 | 11 | - | - |
| San Joaquin | 145 | 51 | 12 | 24% |
| San Luis Obispo | 124 | 9 | - | - |
| San Mateo | 523 | 125 | 9 | 7% |
| Santa Barbara | 74 | 5 | - | - |
| Santa Clara | 902 | 277 | 108 | 39% |
| Santa Cruz | 94 | 8 | - | - |
| Shasta | 25 | 3 | - | - |
| Sierra | - | - | - | - |
| Siskiyou | 3 | - | - | - |
| Solano | 67 | 12 | 2 | 17% |
| Sonoma | 139 | 9 | 1 | 11% |
| Stanislaus | 118 | 15 | 1 | 7% |
| Sutter | 28 | 7 | 3 | 43% |
| Tehama | 5 | - | - | - |
| Trinity | 1 | - | - | - |
| Tulare | 34 | 7 | - | - |
| Tuolumne | 2 | - | - | - |
| Ventura | 119 | 28 | 7 | 25% |
| Yolo | 179 | 83 | 20 | 24% |
| Yuba | 35 | 7 | 3 | 43% |
| State Totals | 8676 | 1991 | 657 | 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