| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 414 | 41 | 7 | 17% |
| Alpine | 1 | - | - | - |
| Amador | 40 | 2 | - | - |
| Butte | 381 | 37 | 5 | 14% |
| Calaveras | 44 | 2 | - | - |
| Colusa | 30 | 6 | 2 | 33% |
| Contra Costa | 1221 | 110 | 14 | 13% |
| Del Norte | 11 | - | - | - |
| El Dorado | 283 | 24 | 2 | 8% |
| Fresno | 977 | 132 | 47 | 36% |
| Glenn | 95 | 7 | - | - |
| Humboldt | 32 | 6 | - | - |
| Imperial | 30 | - | - | - |
| Inyo | 22 | 3 | - | - |
| Kern | 617 | 70 | 23 | 33% |
| Kings | 152 | 25 | 8 | 32% |
| Lake | 39 | 3 | 1 | 33% |
| Lassen | 7 | 1 | - | - |
| Los Angeles | 2014 | 233 | 38 | 16% |
| Madera | 108 | 13 | 7 | 54% |
| Marin | 147 | - | - | - |
| Mariposa | 28 | 3 | - | - |
| Mendocino | 49 | 6 | - | - |
| Merced | 303 | 12 | 2 | 17% |
| Modoc | 13 | 3 | 1 | 33% |
| Mono | 7 | 1 | - | - |
| Monterey | 147 | 9 | - | - |
| Napa | 91 | 2 | - | - |
| Nevada | 96 | 12 | - | - |
| Orange | 862 | 234 | 6 | 3% |
| Placer | 402 | 33 | 3 | 9% |
| Plumas | 25 | - | - | - |
| Riverside | 364 | 13 | 1 | 8% |
| Sacramento | 1423 | 126 | 8 | 6% |
| San Benito | 26 | 4 | - | - |
| San Bernardino | 524 | 61 | 4 | 7% |
| San Diego | 453 | 78 | 14 | 18% |
| San Francisco | 83 | 9 | 1 | 11% |
| San Joaquin | 581 | 78 | 10 | 13% |
| San Luis Obispo | 143 | 14 | - | - |
| San Mateo | 178 | 25 | 1 | 4% |
| Santa Barbara | 63 | 2 | 1 | 50% |
| Santa Clara | 628 | 65 | 8 | 12% |
| Santa Cruz | 169 | 13 | 1 | 8% |
| Shasta | 266 | 39 | 6 | 15% |
| Sierra | - | - | - | - |
| Siskiyou | 6 | 1 | - | - |
| Solano | 262 | 1 | - | - |
| Sonoma | 230 | - | - | - |
| Stanislaus | 594 | 53 | 8 | 15% |
| Sutter | 63 | 4 | - | - |
| Tehama | 51 | 9 | - | - |
| Trinity | 10 | - | - | - |
| Tulare | 392 | 58 | 8 | 14% |
| Tuolumne | 33 | 8 | 1 | 13% |
| Ventura | 265 | 27 | 1 | 4% |
| Yolo | 310 | 27 | 1 | 4% |
| Yuba | 17 | 1 | - | - |
| State Totals | 15822 | 1746 | 240 | 14% |
* 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