| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 1065 | 101 | 3 | 3% |
| Alpine | 6 | 1 | - | - |
| Amador | 112 | 17 | - | - |
| Butte | 1045 | 106 | 21 | 20% |
| Calaveras | 208 | 21 | 2 | 10% |
| Colusa | 50 | 5 | - | - |
| Contra Costa | 2042 | 192 | 7 | 4% |
| Del Norte | 46 | 8 | - | - |
| El Dorado | 441 | 47 | 1 | 2% |
| Fresno | 2010 | 180 | 63 | 35% |
| Glenn | 158 | 41 | 21 | 51% |
| Humboldt | 147 | 15 | - | - |
| Imperial | 11 | 1 | - | - |
| Inyo | 47 | 1 | - | - |
| Kern | 1888 | 146 | 72 | 49% |
| Kings | 191 | 17 | 1 | 6% |
| Lake | 145 | 14 | - | - |
| Lassen | 84 | 11 | 1 | 9% |
| Los Angeles | 2518 | 261 | 5 | 2% |
| Madera | 158 | 20 | - | - |
| Marin | 455 | 38 | - | - |
| Mariposa | 49 | 7 | - | - |
| Mendocino | 115 | 15 | - | - |
| Merced | 484 | 52 | 17 | 33% |
| Modoc | 19 | 1 | - | - |
| Mono | 60 | - | - | - |
| Monterey | 349 | 32 | - | - |
| Napa | 139 | - | - | - |
| Nevada | 326 | 35 | 2 | 6% |
| Orange | 833 | 107 | 9 | 8% |
| Placer | 1002 | 50 | 1 | 2% |
| Plumas | 81 | 10 | - | - |
| Riverside | 649 | 23 | 1 | 4% |
| Sacramento | 5985 | 145 | 19 | 13% |
| San Benito | 56 | 13 | - | - |
| San Bernardino | 795 | 75 | 4 | 5% |
| San Diego | 874 | 132 | 9 | 7% |
| San Francisco | 161 | 17 | - | - |
| San Joaquin | 1581 | 48 | 20 | 42% |
| San Luis Obispo | 322 | 32 | 2 | 6% |
| San Mateo | 585 | 73 | - | - |
| Santa Barbara | 208 | 14 | - | - |
| Santa Clara | 1998 | 128 | 32 | 25% |
| Santa Cruz | 357 | 40 | 1 | 3% |
| Shasta | 808 | 94 | 28 | 30% |
| Sierra | 13 | 2 | - | - |
| Siskiyou | 34 | 2 | - | - |
| Solano | 602 | 7 | 1 | 14% |
| Sonoma | 849 | 92 | 1 | 1% |
| Stanislaus | 1465 | 148 | 67 | 45% |
| Sutter | 255 | 6 | 1 | 17% |
| Tehama | 199 | 28 | 6 | 21% |
| Trinity | 60 | 4 | - | - |
| Tulare | 572 | 41 | 4 | 10% |
| Tuolumne | 146 | 15 | 1 | 7% |
| Ventura | 628 | 73 | - | - |
| Yolo | 648 | 69 | 6 | 9% |
| Yuba | 120 | 8 | 1 | 13% |
| State Totals | 36254 | 2881 | 430 | 15% |
* 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