| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 310 | 62 | 1 | 2% |
| Alpine | - | - | - | - |
| Amador | 20 | - | - | - |
| Butte | 377 | 102 | 6 | 6% |
| Calaveras | 35 | 4 | - | - |
| Colusa | 20 | 14 | 1 | 7% |
| Contra Costa | 924 | 32 | 8 | 25% |
| Del Norte | - | - | - | - |
| El Dorado | 185 | 44 | 2 | 5% |
| Fresno | 427 | 65 | 22 | 34% |
| Glenn | 20 | 14 | 3 | 21% |
| Humboldt | 7 | 1 | - | - |
| Imperial | 6 | - | - | - |
| Inyo | 14 | 2 | - | - |
| Kern | 248 | 43 | 13 | 30% |
| Kings | 45 | 2 | - | - |
| Lake | 74 | 11 | - | - |
| Lassen | 9 | 2 | - | - |
| Los Angeles | 1308 | 251 | 41 | 16% |
| Madera | 73 | 19 | 13 | 68% |
| Marin | 75 | - | - | - |
| Mariposa | 7 | - | - | - |
| Mendocino | 19 | 3 | - | - |
| Merced | 257 | 46 | 14 | 30% |
| Modoc | 14 | 5 | - | - |
| Mono | 12 | 2 | 1 | 50% |
| Monterey | 111 | 17 | - | - |
| Napa | 22 | - | - | - |
| Nevada | 53 | 10 | - | - |
| Orange | 495 | 204 | 17 | 8% |
| Placer | 280 | 71 | 9 | 13% |
| Plumas | 5 | 3 | - | - |
| Riverside | 243 | 5 | 1 | 20% |
| Sacramento | 1320 | 321 | 115 | 36% |
| San Benito | 26 | 4 | - | - |
| San Bernardino | 518 | 104 | 10 | 10% |
| San Diego | 242 | 111 | 2 | 2% |
| San Francisco | 49 | 6 | - | - |
| San Joaquin | 502 | 92 | 26 | 28% |
| San Luis Obispo | 77 | 13 | - | - |
| San Mateo | 165 | 27 | - | - |
| Santa Barbara | 51 | 14 | - | - |
| Santa Clara | 842 | 127 | 32 | 25% |
| Santa Cruz | 76 | 22 | 4 | 18% |
| Shasta | 127 | 35 | 4 | 11% |
| Sierra | 1 | - | - | - |
| Siskiyou | 8 | - | - | - |
| Solano | 137 | 2 | 1 | 50% |
| Sonoma | 143 | - | - | - |
| Stanislaus | 355 | 85 | 34 | 40% |
| Sutter | 40 | 4 | 1 | 25% |
| Tehama | 44 | 9 | - | - |
| Trinity | 5 | - | - | - |
| Tulare | 218 | 43 | 21 | 49% |
| Tuolumne | 19 | 2 | - | - |
| Ventura | 166 | 37 | - | - |
| Yolo | 211 | 43 | 14 | 33% |
| Yuba | 37 | 1 | - | - |
| State Totals | 11074 | 2136 | 416 | 19% |
* 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