| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 1065 | 74 | 2 | 3% |
| Alpine | 6 | - | - | - |
| Amador | 112 | 14 | - | - |
| Butte | 1045 | 64 | 3 | 5% |
| Calaveras | 208 | 19 | 2 | 11% |
| Colusa | 50 | 1 | - | - |
| Contra Costa | 2042 | 168 | 5 | 3% |
| Del Norte | 46 | 7 | - | - |
| El Dorado | 441 | 40 | - | - |
| Fresno | 2010 | 140 | 36 | 26% |
| Glenn | 158 | 28 | 10 | 36% |
| Humboldt | 147 | 15 | - | - |
| Imperial | 11 | 1 | - | - |
| Inyo | 47 | - | - | - |
| Kern | 1888 | 108 | 48 | 44% |
| Kings | 191 | 16 | 1 | 6% |
| Lake | 145 | 12 | - | - |
| Lassen | 84 | 8 | - | - |
| Los Angeles | 2518 | 247 | 3 | 1% |
| Madera | 158 | 18 | - | - |
| Marin | 455 | 34 | - | - |
| Mariposa | 49 | 7 | - | - |
| Mendocino | 115 | 12 | - | - |
| Merced | 484 | 35 | 5 | 14% |
| Modoc | 19 | 1 | - | - |
| Mono | 60 | - | - | - |
| Monterey | 349 | 30 | - | - |
| Napa | 139 | - | - | - |
| Nevada | 326 | 24 | 1 | 4% |
| Orange | 833 | 107 | 9 | 8% |
| Placer | 1002 | 43 | - | - |
| Plumas | 81 | 8 | - | - |
| Riverside | 649 | 23 | 1 | 4% |
| Sacramento | 5985 | 120 | 5 | 4% |
| San Benito | 56 | 12 | - | - |
| San Bernardino | 795 | 67 | 3 | 4% |
| San Diego | 874 | 118 | 6 | 5% |
| San Francisco | 161 | 16 | - | - |
| San Joaquin | 1581 | 29 | 5 | 17% |
| San Luis Obispo | 322 | 25 | - | - |
| San Mateo | 585 | 65 | - | - |
| Santa Barbara | 208 | 11 | - | - |
| Santa Clara | 1998 | 112 | 25 | 22% |
| Santa Cruz | 357 | 39 | - | - |
| Shasta | 808 | 66 | 13 | 20% |
| Sierra | 13 | 2 | - | - |
| Siskiyou | 34 | 2 | - | - |
| Solano | 602 | 7 | 1 | 14% |
| Sonoma | 849 | 85 | - | - |
| Stanislaus | 1465 | 121 | 42 | 35% |
| Sutter | 255 | 5 | 1 | 20% |
| Tehama | 199 | 20 | 1 | 5% |
| Trinity | 60 | 2 | - | - |
| Tulare | 572 | 29 | 1 | 3% |
| Tuolumne | 146 | 10 | 1 | 10% |
| Ventura | 628 | 70 | - | - |
| Yolo | 648 | 43 | 1 | 2% |
| Yuba | 120 | 8 | 1 | 13% |
| State Totals | 36254 | 2388 | 232 | 10% |
* 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