Updated Monday, 8 a.m.
A heat advisory is in effect from 10 a.m. through 9 p.m. Monday. Weather forecasters say temperatures will reach record or near-record highs Monday afternoon — about 90 degrees for San Francisco.
Officials are warning of heat-related illnesses and they're encouraging people to drink plenty of fluids, to stay in air-conditioned rooms and to avoid the sun. Authorities have also issued a Spare the Air smog alert for Monday.
Updated Sunday, 6 p.m.
Just two weeks after rain and cool temperatures put a damper on many Bay Area Memorial Day weekend plans, the region is getting its first real heat wave of the year.
Record or near-record temperatures registered across the Bay Area on Sunday. Downtown San Francisco tied a 33-year-old record high at 91 degrees, the same temperature recorded at the Oakland Airport, a full 5 degrees higher than its previous record. Half Moon Bay obliterated its previous June 9 high of 72 degrees in 1941 with an 86-degree scorcher on Sunday.
Much of the North Bay and South Bay neared triple-digit temperatures on Sunday, and the heat is expected to be even worse on Monday, with several cities forecast to break 100 degrees. The National Weather Service issued heat advisories for much of the Bay Area on Sunday and Monday.
"Sensitive populations like the elderly, children, even pets should pay special attention to staying cool because they're the most vulnerable in these types of situations," said National Weather Service meteorologist Spencer Tangen.
Residents in San Francisco looking to cool off are encouraged to go to:
Alameda, Marin and Santa Clara counties also have several cooling centers for their residents to avoid the heat.
The hot temperatures combined with high winds are prompting fire concerns. The weather service issued a red-flag warning for the North Bay mountains on Friday night that lasts through Sunday afternoon, meaning that any fires that start could spread quickly due to high winds, high temperatures and low humidity.
PG&E on Saturday preemptively cut power to around 1,600 customers in Napa, Solano and Yolo counties and another 20,500 in Butte and Yuba counties because of the fire danger.
Several vegetation fires sparked across the region over the weekend, including the Sand Fire in Yolo County, which sent smoke drifting into parts of the Bay Area. As of Sunday evening, the Sand Fire had burned 2,200 acres and was 20% contained, according to Cal Fire.
“Be very careful if you’re out in grassy areas," Tangen said. "With the strong winds and the very dry conditions, any spark could very easily ignite a fire, especially if you’re in a grassy area where the fuel is very dry.”
Tangen said even though the region just finished its wettest May in more than 20 years, finer fuels like grass dry out very quickly.
The high temperatures and winds also prompted the Bay Area Air Quality Management District to issue the year's first Spare the Air smog alert on Sunday — days earlier than the first alert last year — and a second alert for Monday. Officials expect ozone pollution to reach unhealthy levels and are asking people to avoid driving to limit the vehicle exhaust in the air.
KQED's Jeremy Siegel contributed to this report.
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