| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 706 | 74 | - | - |
| Alpine | 3 | - | - | - |
| Amador | 110 | 14 | 1 | 7% |
| Butte | 751 | 54 | 8 | 15% |
| Calaveras | 129 | 18 | - | - |
| Colusa | 46 | 2 | - | - |
| Contra Costa | 2227 | 153 | 16 | 10% |
| Del Norte | 27 | - | - | - |
| El Dorado | 543 | 49 | 1 | 2% |
| Fresno | 1232 | 93 | 4 | 4% |
| Glenn | 92 | 13 | 2 | 15% |
| Humboldt | 78 | 3 | - | - |
| Imperial | 35 | - | - | - |
| Inyo | 35 | 4 | - | - |
| Kern | 1590 | 166 | 4 | 2% |
| Kings | 133 | 8 | - | - |
| Lake | 94 | 4 | - | - |
| Lassen | 23 | 2 | - | - |
| Los Angeles | 5535 | 318 | 84 | 26% |
| Madera | 121 | 19 | - | - |
| Marin | 219 | 18 | - | - |
| Mariposa | 18 | 2 | - | - |
| Mendocino | 79 | 8 | - | - |
| Merced | 207 | 16 | - | - |
| Modoc | 17 | - | - | - |
| Mono | 11 | 1 | - | - |
| Monterey | 272 | 16 | 2 | 13% |
| Napa | 88 | 2 | - | - |
| Nevada | 305 | 47 | 3 | 6% |
| Orange | 2996 | 337 | 155 | 46% |
| Placer | 724 | 10 | 1 | 10% |
| Plumas | 57 | 12 | - | - |
| Riverside | 1269 | 53 | 13 | 25% |
| Sacramento | 3106 | 259 | 39 | 15% |
| San Benito | 34 | 2 | - | - |
| San Bernardino | 1554 | 126 | 27 | 21% |
| San Diego | 1742 | 250 | 122 | 49% |
| San Francisco | 105 | 10 | - | - |
| San Joaquin | 1509 | 158 | 49 | 31% |
| San Luis Obispo | 180 | 15 | - | - |
| San Mateo | 389 | 51 | 1 | 2% |
| Santa Barbara | 96 | 8 | - | - |
| Santa Clara | 961 | 55 | 7 | 13% |
| Santa Cruz | 163 | 14 | - | - |
| Shasta | 406 | 17 | 6 | 35% |
| Sierra | 16 | 1 | - | - |
| Siskiyou | 21 | 2 | - | - |
| Solano | 542 | 13 | 4 | 31% |
| Sonoma | 495 | 56 | - | - |
| Stanislaus | 938 | 86 | 19 | 22% |
| Sutter | 179 | 7 | 2 | 29% |
| Tehama | 137 | 15 | - | - |
| Trinity | 14 | 1 | - | - |
| Tulare | 754 | 151 | 64 | 42% |
| Tuolumne | 92 | 6 | - | - |
| Ventura | 553 | 49 | 3 | 6% |
| Yolo | 534 | 24 | 1 | 4% |
| Yuba | 103 | 8 | - | - |
| State Totals | 34395 | 2900 | 638 | 22% |
* 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