| County | Reported* | Tested | Positive | % Tested Positive |
| Alameda | 491 | 82 | 78 | 95% |
| Alpine | - | - | - | - |
| Amador | 2 | - | - | - |
| Butte | 70 | 18 | 2 | 11% |
| Calaveras | 5 | - | - | - |
| Colusa | 9 | 4 | 2 | 50% |
| Contra Costa | 546 | 131 | 95 | 73% |
| Del Norte | - | - | - | - |
| El Dorado | 56 | 17 | 4 | 24% |
| Fresno | 135 | 10 | 1 | 10% |
| Glenn | 3 | - | - | - |
| Humboldt | 8 | - | - | - |
| Imperial | 2 | - | - | - |
| Inyo | 1 | - | - | - |
| Kern | 16 | 2 | - | - |
| Kings | 13 | - | - | - |
| Lake | 24 | 16 | 8 | 50% |
| Lassen | - | - | - | - |
| Los Angeles | 800 | 128 | 44 | 34% |
| Madera | 29 | 12 | 1 | 8% |
| Marin | 47 | 4 | 2 | 50% |
| Mariposa | 2 | - | - | - |
| Mendocino | 17 | 2 | - | - |
| Merced | 40 | 2 | - | - |
| Modoc | - | - | - | - |
| Mono | 4 | - | - | - |
| Monterey | 16 | 1 | - | - |
| Napa | 28 | 10 | 4 | 40% |
| Nevada | 17 | 6 | 1 | 17% |
| Orange | 165 | 43 | 2 | 5% |
| Placer | 273 | 146 | 43 | 29% |
| Plumas | - | - | - | - |
| Riverside | 257 | 113 | 69 | 61% |
| Sacramento | 923 | 456 | 196 | 43% |
| San Benito | 8 | 2 | 1 | 50% |
| San Bernardino | 118 | 25 | 11 | 44% |
| San Diego | 208 | 90 | 9 | 10% |
| San Francisco | 64 | 13 | - | - |
| San Joaquin | 150 | 43 | 20 | 47% |
| San Luis Obispo | 34 | 12 | 1 | 8% |
| San Mateo | 333 | 78 | 14 | 18% |
| Santa Barbara | 16 | 10 | - | - |
| Santa Clara | 625 | 198 | 117 | 59% |
| Santa Cruz | 40 | 12 | - | - |
| Shasta | 23 | 6 | 2 | 33% |
| Sierra | - | - | - | - |
| Siskiyou | 1 | - | - | - |
| Solano | 121 | 42 | 18 | 43% |
| Sonoma | 173 | 25 | 16 | 64% |
| Stanislaus | 162 | 13 | 6 | 46% |
| Sutter | 47 | 11 | 6 | 55% |
| Tehama | 7 | - | - | - |
| Trinity | - | - | - | - |
| Tulare | 51 | 12 | 5 | 42% |
| Tuolumne | 3 | - | - | - |
| Ventura | 88 | 25 | 4 | 16% |
| Yolo | 333 | 132 | 67 | 51% |
| Yuba | 25 | 3 | - | - |
| State Totals | 6629 | 1955 | 849 | 43% |
* 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