The newest restrictions require people to stay home from 10 p.m. to 5 a.m. unless they are responding to an emergency, shopping for groceries, picking up takeout or walking their dogs. The curfew will last until Dec. 21, with a possible extension if rapidly worsening trends don't improve.
RELATED: Gov. Newsom orders curfew for most California counties
Authorities say the focus is on keeping people from social mixing and drinking -- the kinds of activities that are blamed for causing COVID-19 infections to soar after dipping only a few months ago. ABC7 News' Cornell Barnard and Luz Pena went to see how businesses are getting ready and how some local police departments are planning to enforce the curfew.
James Robledo, co-owner of Carmen's Bistro and Bar on 4th Street in Santa Rosa is pivoting once again and shifting his restaurant's closing time, which will impact weekend business that's already struggling.
"We're aiming at 9 p.m. last call, stop seating people at that time, get cleaned up in kitchen to be out by 10," Robeldo said.
For Alameda County business owners like Stanley Yee, closing early is what they've been doing even before the curfew.
"The town started shutting down on its own early in the evening. Nobody is open until midnight nowadays," said Yee, owner of Town Tavern.
WATCH: Alameda businesses close early as curfew begins
Yee is hoping the curfew brings an earlier clientele, "If folks can come and spread out the time and come a little earlier they can have their fun and get home before curfew."
Two blocks from Town Tavern, we found the Alameda Comedy Club. They opened in the middle of the pandemic and tonight they had a strict start time.
"But now it's like when the show starts, the show starts. We have hard deadline to get off stage," said Patrick Ford, Alameda Comedy Club Co-owner. "No later than 9:40 p.m."
Dr. Mark Cullen, an infectious disease expert who recently retired from Stanford University, said the underlying goal is based on a reasonable interpretation of data.
"Large numbers of people getting together oblivious of controls -- no masks, no social distancing, often indoors-- a lot of those things are in fact occurring at night,'' Cullen said. However, he also questioned whether a limited curfew will be effective.
MAP: CA counties that can, can't reopen under new rules
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The curfew applies to 41 of the state's 58 counties that are in the "purple'' tier, the most restrictive of four state tiers allowing various stages of economic reopening. Those counties encompass 94% of the nearly 40 million people living in the most populous U.S. state.
California as a whole has seen more than 1 million infections, with a record of almost 15,500 new cases reported Friday.
Officials hope to avoid full-on lockdown orders of the kind enacted back when the COVID-19 pandemic was gaining steam in March. Public health officials since then have reacted to swings in infection rates by easing and then reinforcing various stay-at-home orders in an effort to balance safety and the economy.
The result, however, has been confusion and what some health officials term "COVID fatigue" in which people simply become tired of the rules and let down their guard.
VIDEO: Dr. Fauci's hopeful message to those with COVID-19 fatigue: 'Help is really on the way'
Health officials acknowledge that the curfew will help flatten the infection rates only if people heed it voluntarily. Violators could face fines or be charged with a misdemeanor, and businesses could have their business licenses revoked. But counties are mainly responsible for enforcement.
Solano, Sonoma counties are among several other counties across the state saying they won't actively enforce the curfew. Officials in El Dorado, Fresno, Los Angeles, Orange, Placer, Sacramento, San Bernardino and Stanislaus counties also say they won't enforce the order, with some strongly opposed.
"We're not going to be actively stopping cars after 10 p.m., or looking for people walking around, but we do want people to abide and be home by 10," Sargeant Christopher Mahurin with the Santa Rosa Police Department said.
The Solano County Sheriff's office says, they are aware and will not respond to calls for service solely based on non-compliance with public health orders.
"I don't believe you're more susceptible to COVID between 10 and 5, apparently that's a thing," Sonoma County resident Nadine Thomas said.
Tod Lasman of Alameda County said, "I don't understand how this can keep happening? Like a rolling blackout. It happens and it stops, it happens and it stops."
RELATED: How will California's new curfew work? Will it be effective? UCSF doctor weighs in
In Southern California, West Hollywood, famously known for its clubs and vibrant LGBT community, "will be impacted like no other city" by the curfew, Mayor Lindsey Horvath said.
"These businesses have created places, safe places for our LGBT community to go out in particular, to enjoy our nightlife, to be together in community," Horvath said. "It's terribly heartbreaking to see what's happening right now.''
The curfew even could be counterproductive, said Dr. Lee Riley, an infectious disease professor at the University of California, Berkeley, School of Public Health.
Officials in London who tried a similar approach found that "if anything, for the young people it may have increased their social gathering activities,'' he said. "They can't go out, so they congregate in somebody's home or dormitories.''
"I'm not sure how effective this is going to be,'' Riley said. But the state feels that they have to do something. I think it's going to be mostly a cosmetic effect and not so much a real impact on interrupting this transmission.''
The Associated Press contributed to this report.
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