In May, after prospective buyers outbid each other in a walk-through, a house on Arroyo Road in Lagunitas sold for $2.1 million. News that the house went for almost 25 percent over its asking price trickled down to another nearby homeowner; soon, renter Adam Vurek, his girlfriend and his 12-year-old son were asked to leave their home of six years.

Mr. Vurek said another tenant on the property had missed her rent during the pandemic and his landlords were under financial pressure. He also knew they were in a hurry to sell, concerned about missing the window of time when the market was up. When they heard the Lagunitas house sold for as much as it did, the prospect of selling was too good to pass up. 

“I totally understand my landlords hearing that and making the call that it’s a good time to sell,” Mr. Vurek said, “but it doesn’t suck any less.”

As West Marin’s real estate market booms, homeowners are selling for upwards of 35 percent over asking price, but renters aren’t seeing any windfalls. The boom, which longtime realtor B.G. Bates described as getting “crazier and crazier,” is making the market even more precarious for those who don’t own property. 

A combination of factors has pushed real estate prices up since last year. Interest rates are low, and Marin’s limited housing supply became more desirable to wealthy people leaving cities. Ms. Bates said this led to a chain reaction. “People look at the last deal that happened, they see how much the buyer went over, and they use the same formula,” she said.

In June, about 90 single-family homes sold in unincorporated Marin, at an average price of just over $2.2 million. 

“We’ve never had higher prices, but they’re not going to go down,” said realtor William Barrett, who has lived in West Marin for 40 years. He said the unique rural character of the area, where protected lands have kept housing scarce, makes it desirable as vacation territory for rich buyers.  

“Buyers are not coming out here because they have a job here or want their kids to go to school here,” Mr. Barrett said. “Buyers are coming out here because this is their third or fourth house, and they’ve always wanted one out here.”

Realtors agree that with its low inventory, the market in this part of the county is unlikely to cool down for some time. Only a natural disaster like a major earthquake or wildfire could pop the bubble, Mr. Barrett speculated. Otherwise, there will always be enough wealthy buyers to keep prices high. And once people buy a house here, they don’t tend to leave for a long time. “Demand always outstrips supply out here, always,” he said. 

Mr. Barrett criticized the wariness felt by some locals toward newcomers as “xenophobia.” He said most of his customers already know the area and are looking to be a part of the community. But he acknowledged the angst felt by West Marin renters. “There’s a justifiable fear among people who live out here who are not property owners that every newcomer who comes in is upping the ante for the value of the houses,” he said. 

Few protections are in place for renters along the coast, where single-family homes far outnumber apartment buildings. The county’s 2019 just-cause ordinance, which requires landlords in unincorporated Marin to give tenants a reason for eviction, applies only to properties with three or more units, excluding most West Marin tenants. The ordinance allows no-fault evictions for landlords planning to either move into the unit or permanently remove it from the rental market. 

Renters saw some new protections pass on the state level in response to the pandemic. The state extended until September its ban on evictions for nonpayment of rent due to Covid-related financial hardship. The same bill, A.B. 832, also requires that if a landlord wants to evict a tenant and sell the property, he or she must already have a contract with a buyer who intends to occupy the property. 

It may not be difficult to find buyers for expensive property in West Marin, but it can be nearly impossible to find an affordable unit as a renter. Sparse options in West Marin are forcing tenants who have lived in the area for much of their lives to consider moving elsewhere. Leonor Saccomano and her husband, Vince, have rented the same home in Inverness for 16 years, without ever missing a payment. Last month, their landlord gave them until mid-August to leave; he plans to sell another home he owns in Inverness and move into the rental, Ms. Saccomano said.  

“He’s in a hurry to sell his home, because they’re selling for more than their asking price,” she said. 

The Saccomanos are retired lifelong West Marin residents, and it’s difficult for them to imagine moving anywhere else. “It’s too hard to think about it,” but she added: “We’ll have to go somewhere.” 

Mr. Vurek, who lost his rental in the valley, recently signed a lease in Camp Meeker, in Sonoma County. He made what he called the heartbreaking decision to leave Marin after weeks of combing bulletin boards and online forums for housing in the community. 

“A single dad doesn’t look that great to landlords a lot of the time,” he said.

Lagunitas School, where Mr. Vurek teaches a skateboarding elective and where his son is a student, was the biggest reason he hoped to stay in the valley. He’s still working with the Valley Skate Club but isn’t sure he’ll be able to keep teaching. 

Schools have had trouble adapting to the unaffordable rental market. Mr. Vurek said the Open Classroom program has seen less participation from parent volunteers in recent years as both parents in households have to work to afford rent. 

The Bolinas-Stinson Union School District sent a postcard to residents last month about its search for teacher housing. “As you know, the increased cost of housing in Stinson Beach and Bolinas has been dramatic, far outpacing wage growth for our public school staff who live and work in this community,” the mailer read. “Our school is better when educators have the opportunity to work and live in our community.”

The district is seeking all sizes of rentals for “more sustainable, long-term” housing.

In Point Reyes Station, Zoe Crowhurst is in search of a new home for both her preschool program and her family, after her landlord told her she plans to move into the house. She’s found two leads in months of looking, and neither one panned out. 

“Always knowing that we may have to move impacts every decision that we make as a family,” she said.

Ms. Crowhurst started Little Sparrows in her home last year after the pandemic forced Huckleberry Garden, the preschool where she taught, to split up. That program has had many incarnations and homes, she said, because it’s so difficult to find a space in West Marin. She hopes to soon have a more permanent home for her own program. “Rooting these kids in a sense of community is integral to our work here,” she said.