| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 260 | 49 | - | - |
| Alpine | - | - | - | - |
| Amador | 18 | - | - | - |
| Butte | 222 | 55 | - | - |
| Calaveras | 20 | 1 | - | - |
| Colusa | 17 | 5 | - | - |
| Contra Costa | 1059 | 79 | 38 | 48% |
| Del Norte | 1 | - | - | - |
| El Dorado | 124 | 30 | 2 | 7% |
| Fresno | 334 | 52 | 15 | 29% |
| Glenn | 23 | 13 | 2 | 15% |
| Humboldt | 17 | 5 | - | - |
| Imperial | 1 | - | - | - |
| Inyo | 24 | 1 | - | - |
| Kern | 274 | 55 | 4 | 7% |
| Kings | 67 | 19 | 9 | 47% |
| Lake | 20 | 5 | 1 | 20% |
| Lassen | 13 | 1 | - | - |
| Los Angeles | 1983 | 440 | 227 | 52% |
| Madera | 62 | 14 | 3 | 21% |
| Marin | 60 | - | - | - |
| Mariposa | 4 | - | - | - |
| Mendocino | 15 | 4 | - | - |
| Merced | 178 | 25 | 9 | 36% |
| Modoc | 1 | 1 | - | - |
| Mono | 7 | 1 | - | - |
| Monterey | 42 | 9 | - | - |
| Napa | 27 | 1 | - | - |
| Nevada | 57 | 17 | 1 | 6% |
| Orange | 522 | 198 | 50 | 25% |
| Placer | 225 | 50 | 10 | 20% |
| Plumas | 13 | - | - | - |
| Riverside | 208 | 33 | 7 | 21% |
| Sacramento | 1244 | 470 | 134 | 29% |
| San Benito | 15 | 4 | - | - |
| San Bernardino | 435 | 112 | 33 | 29% |
| San Diego | 194 | 103 | - | - |
| San Francisco | 35 | 1 | - | - |
| San Joaquin | 374 | 73 | 27 | 37% |
| San Luis Obispo | 85 | 16 | - | - |
| San Mateo | 176 | 22 | - | - |
| Santa Barbara | 73 | 11 | - | - |
| Santa Clara | 675 | 185 | 35 | 19% |
| Santa Cruz | 72 | 5 | - | - |
| Shasta | 109 | 43 | - | - |
| Sierra | - | - | - | - |
| Siskiyou | 3 | - | - | - |
| Solano | 143 | 7 | 1 | 14% |
| Sonoma | 120 | - | - | - |
| Stanislaus | 379 | 68 | 24 | 35% |
| Sutter | 33 | 8 | 2 | 25% |
| Tehama | 50 | 9 | 1 | 11% |
| Trinity | 3 | - | - | - |
| Tulare | 334 | 80 | 42 | 53% |
| Tuolumne | 14 | 3 | - | - |
| Ventura | 178 | 38 | 1 | 3% |
| Yolo | 175 | 67 | 9 | 13% |
| Yuba | 38 | 1 | 1 | 100% |
| State Totals | 10855 | 2489 | 688 | 28% |
* 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