More than half of the state's 40 million people will be subject to a stay-at-home order, as announced by Governor Gavin Newsom on Thursday.
Many businesses will be closed, and people will be banned from meeting anyone outside their household.
The order was triggered by intensive care capacity in hospitals shrinking.
The southern part of the state and its central valley will be the first areas to come under the new restrictions, at 23:59 local time on Sunday (07:59 GMT on Monday).
Other areas could follow within days. San Francisco will have its own local lockdown also starting on Sunday.
California's lockdown in March, in which all non-essential businesses were closed, was seen as an early model for the US at the beginning of the pandemic.
The measures come after the US reported on Saturday a record number of coronavirus cases in 24 hours for the third day in a row - 230,000.
In the same period, 2,527 deaths were recorded. For the past two weeks, the US has regularly seen more than 2,000 deaths a day, similar to the early days of the pandemic.
The surge could be partly down to last week's Thanksgiving holiday, when millions of Americans travelled around the country.