Bay Area residents must wear face coverings in public starting this weekend, a practice that likely will become ingrained as leaders look to ease restrictions on social and commercial life.

Mayor London Breed announced the rules for San Francisco on Friday, which will apply to people riding transit, working at essential businesses, doing construction, grocery shopping, standing in line at a store or doing anything else that puts them near others.

“Any time you’re indoors or within close proximity of others within an essential business, you will be required to wear a mask,” Breed said during her afternoon briefing. She stressed that face coverings will not replace the 6 feet of separation that experts have recommended for social distancing.

The order is part of a regional effort that will require residents of several counties to wear cloth coverings.

Health directors of Marin, Alameda, San Mateo and Contra Costa counties released similar mandates Friday, following the lead of Sonoma County, which delivered the first order early this week.

Santa Clara County stopped short of issuing a health order to require face masks. Instead, health officers on Friday issued expanded guidance “strongly urging” all individuals to wear face coverings when performing essential duties in public. The county said in a statement the guidance is meant to “achieve the same goals” as other counties that issued enforceable requirements.

San Francisco’s order, issued by City and County Health Officer Dr. Tomás Aragón, takes effect at 11:59 p.m. Friday night, though the city will wait until 8 a.m. on Wednesday to enforce it.

Residents will not be required to wear protective gear to simply walk down the street, jog, hike or a ride a bicycle.

Breed characterized face masks as a “new normal” to which residents will have to acclimate. City Public Health Director Dr. Grant Colfax echoed that sentiment.

“It is important to understand that today’s order is part of a broader strategy to establish new ways of interacting and behaving,” Colfax said. The hope, he added, is for Bay Area residents to be in the habit of donning protective gear whenever they shop, hail a taxi, hop on a bus, or go about everyday life.

Relaxing the stay-at-home orders may mean that masks become entwined in the fabric of everyday life, Colfax and other health experts signaled.

“It is likely that we will need to continue to do this for some time, even after we start to emerge from our homes,” Colfax said.

Officials will not apply the new rules to children 12 or younger, and they’ve discouraged parents from putting masks on children under 3. Health directors are also trying to dissuade people from purchasing medical-grade gear, such as N95 masks, which are in short supply and should be reserved for hospitals. San Francisco is working to distribute coverings to vulnerable populations, which include homeless people, the elderly and the disabled.

Gov. Gavin Newsom said Friday that he is eyeing a statewide mask order as he and other leaders take interim steps to reopen California.

“We are leaning in that direction, and we are very encouraged by the work that’s being done at the local level all throughout the state of California,” Newsom said Friday, referring not only to the Bay Area, but also to an order that came down this week in Los Angeles.

Although Newsom encourages face coverings and said his “entire household” wears them to go to the grocery store, he has never worn one during his daily briefings at the State Operations Center.

“If you saw the protocols to get in this room, you would understand how secure and protected this room is,” he said.

Breed and Aragón released a statement with guidelines that face garments fit securely and fully cover the nose and mouth. They recommended homemade masks, bandannas, scarves, towels or neck gaiters, and advised that the cloth be washed frequently with soap and water.

The order carries the force of law, their statement said, and in San Francisco, “noncompliance is a misdemeanor punishable by fine, imprisonment, or both.” Nonetheless, Breed admonished San Francisco residents not to police each other, as she stood at a flag-draped podium on Friday afternoon.

“What we don’t want is more confrontation, more stress, and more drama in general as a result of this order,” she said.

Matt Willis, public health officer for Marin County, described masks as the next step to make the coronavirus recede, even as the rate of new coronavirus cases slows down in Bay Area cities and counties.

“We’ve seen the shelter-in-place order, thus far, has successfully flattened the curve, but that doesn’t mean we’re out of the woods by any means,” Willis said. He noted that 25% of people who contract the coronavirus may never exhibit symptoms — a glaring concern for medical workers, as it suggests the virus may continue to spread, undetected.

He and other officials hope the new face covering rule will help stave off that proliferation.

Although Friday’s order lays the groundwork to eventually relax shelter-in-place rules, counties will still uphold the original order at least until May 3, when it’s set to expire. So far, none of them have announced steps to reopen the Bay Area after that date.

“The vast majority of members of community remain susceptible to COVID-19, so we need to be extremely cautious making any changes to shelter in place,” Willis said.

Chronicle staff writers Alexei Koseff, Carolyn Said and Anna Bauman contributed to this report.

Rachel Swan is a San Francisco Chronicle staff writer. Email: rswan@sfchronicle