This declaration comes in the wake of record-breaking heat and drought in the state for the second year in a row.
The declaration will enable the state to provide additional resources and funding under the California Disaster Assistance Act to all 58 counties.
In July this year, the governor had signed an order declaring a drought emergency in 50 counties. The new order on Tuesday added the remaining eight counties - Imperial, Los Angeles, Orange, Riverside, San Bernardino, San Diego, San Francisco and Ventura.
In a news release, the governor's office said California is experiencing its worst drought since the late 1800s, that August 2021 was the driest and hottest August on record since reporting began, and that the water year that ended last month was the second driest on record.
Tuesday's order urged the state's residents to step up conservation efforts but did not include any mandates. California experienced another dry winter last year with low snow totals, and extreme heat has affected the state and the entire U.S. West Coast.