| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 1065 | 245 | 19 | 8% |
| Alpine | 6 | 2 | - | - |
| Amador | 112 | 31 | 1 | 3% |
| Butte | 1045 | 124 | 27 | 22% |
| Calaveras | 208 | 39 | 3 | 8% |
| Colusa | 50 | 12 | 4 | 33% |
| Contra Costa | 2042 | 314 | 28 | 9% |
| Del Norte | 46 | 11 | - | - |
| El Dorado | 441 | 107 | 7 | 7% |
| Fresno | 2010 | 294 | 114 | 39% |
| Glenn | 158 | 65 | 36 | 55% |
| Humboldt | 147 | 46 | 2 | 4% |
| Imperial | 11 | 2 | - | - |
| Inyo | 47 | 5 | 1 | 20% |
| Kern | 1888 | 333 | 124 | 37% |
| Kings | 191 | 36 | 9 | 25% |
| Lake | 145 | 22 | 3 | 14% |
| Lassen | 84 | 25 | 2 | 8% |
| Los Angeles | 2518 | 676 | 165 | 24% |
| Madera | 158 | 35 | 6 | 17% |
| Marin | 455 | 71 | 4 | 6% |
| Mariposa | 49 | 9 | - | - |
| Mendocino | 115 | 27 | 3 | 11% |
| Merced | 484 | 97 | 34 | 35% |
| Modoc | 19 | 7 | 1 | 14% |
| Mono | 60 | 4 | - | - |
| Monterey | 349 | 57 | - | - |
| Napa | 139 | 8 | 2 | 25% |
| Nevada | 326 | 86 | 5 | 6% |
| Orange | 833 | 238 | 43 | 18% |
| Placer | 1002 | 98 | 16 | 16% |
| Plumas | 81 | 25 | 1 | 4% |
| Riverside | 649 | 41 | 6 | 15% |
| Sacramento | 5985 | 381 | 142 | 37% |
| San Benito | 56 | 24 | - | - |
| San Bernardino | 795 | 161 | 26 | 16% |
| San Diego | 874 | 328 | 108 | 33% |
| San Francisco | 161 | 40 | 1 | 3% |
| San Joaquin | 1581 | 96 | 46 | 48% |
| San Luis Obispo | 322 | 84 | 9 | 11% |
| San Mateo | 585 | 150 | 2 | 1% |
| Santa Barbara | 208 | 30 | 1 | 3% |
| Santa Clara | 1998 | 275 | 83 | 30% |
| Santa Cruz | 357 | 85 | 6 | 7% |
| Shasta | 808 | 135 | 48 | 36% |
| Sierra | 13 | 4 | - | - |
| Siskiyou | 34 | 9 | 4 | 44% |
| Solano | 602 | 19 | 3 | 16% |
| Sonoma | 849 | 159 | 19 | 12% |
| Stanislaus | 1465 | 262 | 130 | 50% |
| Sutter | 255 | 6 | 1 | 17% |
| Tehama | 199 | 53 | 20 | 38% |
| Trinity | 60 | 14 | 1 | 7% |
| Tulare | 572 | 136 | 38 | 28% |
| Tuolumne | 146 | 36 | 1 | 3% |
| Ventura | 628 | 171 | 15 | 9% |
| Yolo | 648 | 140 | 25 | 18% |
| Yuba | 120 | 8 | 1 | 13% |
| State Totals | 36254 | 5998 | 1396 | 23% |
* 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