The San Francisco Office of Emergency Management says five library branches with air conditioning are cooling centers for residents who need to get out of the heat: Chinatown, Glen Park, Mission Bay, North Beach, and Portrero Hill library branches.
"Anytime it's that hot, especially in the city, the concrete jungle, it's going to be even warmer," said Justin Schorr, Rescue Captain and spokesman with the San Francisco Fire Department, "Many of our neighbors especially elderly and special needs may not have air conditioning so it'll be important to not only stay hydrated ourselves but check in on our neighbors."
"Normally I'd be wearing a hoodie and a hat, but I was sweating my butt off in a t-shirt," said Ali Woolwich, a San Francisco theater union worker, "
"People get heat stroke that didn't expect it and get dehydrated," said Woolwich, "By the time you feel the heat, it's way to late."
San Francisco's usually mild temperatures mean most homes aren't prepared for heat spikes.
"We do not have air conditioning. It's an older building in this neighborhood," said Chris Labarthe, a San Francisco resident in the Nob Hill area.
Downtown inside the bar called The Summer Place, people were cooling off with a drink.
"We have about eight fans going right now," said the owner, Brett Frost, who laughed when questioned about his name, "It's really Frost. I know right? (chuckling) Swear to God. "
Frost says he's ready for the heat to end and get back to San Francisco's fog and cold.
"We can't wait for the cold to come back. We've got a fireplace ready to go," said Frost.
Health officials say it's important to wear loose clothing and hydrate.
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"I hydrate, I drink lots of water 8-10 glasses a day," said Sylvia DeWitt, a Berkeley resident who was walking along Ocean Beach in San Francisco with her friend Joyce Lewis of San Francisco who lives nearby.
The heat is expected to drive many people to the beaches.
"We don't have a lifeguard so people when they come out here to the beach I highly recommend, especially if they have young children, they don't turn their backs on the beach and supervise their children," said Lewis.
First responders say Thursday's high surf and beach danger warnings mean sneaker waves and riptides could sweep unsuspecting beach goers out to sea.
"You can be a comfortable confident swimmer and be in ankle-deep water and a sneaker wave could knock you down and drag you out," said Fire Capt. Schorr, "We recommend if you find yourself unable to swim to shore. Stop. Calm down. Take a deep breath. Swim parallel to the beach, side to side until you feel the pull recede. Then you'll be able to swim toward the beach."
The high surf advisory is set to expire at 7 p.m. Thursday evening.