A total of 28 counties - including Alameda, Contra Costa, Santa Clara, Napa, Santa Cruz and Solano counties - will be moved into the most-restrictive "purple tier" on Tuesday, part of what Newsom described as the state "pulling the emergency brake" on its reopening plans.
In addition, Marin, San Francisco and San Mateo counties moved into the red tier, the second most-restrictive tier in the system.
According to Newsom, the state has seen its quickest increase in new cases statewide over the last 10 days since the pandemic began in earnest in March.
"Every age group, every demographic, racial, ethnic (group) in every part of the state, we are seeing case rates increase and positivity rates increase as well," Newsom said during his Monday afternoon briefing on the pandemic.
"We are seeing community spread broadly," he added.
The only counties in the greater Bay Area that did not move to a stricter tier were Sonoma and Monterey counties, which were already in the purple tier.
The state has also tweaked the way counties are assigned to tiers, moving them to a more-restrictive tier after only one week of rising cases rather than the previously established two.
Newsom said state officials are considering additional measures such as a statewide curfew to discourage people from social gatherings that increase the risk of spreading the coronavirus.
The tier changes will take effect Tuesday.