As temperatures cranked up 
Tuesday – well past 100 degrees in parts of the Bay Area, tying or breaking five heat records from as long ago as 1970 – the National Weather Service delivered news that hardly offered any relief.
“Nothing is pushing this high pressure,” NWS meteorologist Nicole Sarment said. “It’s just staying stagnant and showing no signs of breaking down anytime soon. So this is going to be going on a while, maybe longer than we thought.”
The exceptionally hot blast began with as much intensity as forecasters anticipated, and as of Tuesday they were saying to prepare for an even longer sweat than they predicted earlier.
In the East Bay, Oakland hit 90 degrees, breaking the previous record of 89 set in 2001.
Records also fell in the North Bay. San Rafael and Kentfield both recorded a high of 103 degrees, toppling their previous records of 101 set in 1991. And Santa Rosa reached 105 degrees. That was two degrees warmer than the previous record set in 1970.
San Jose, meanwhile, tied its previous record of 102 degrees set in 1970.
Other highs around the region included 107 degrees in Concord, 106 degrees in Livermore, 99 degrees in Hayward, 98 degrees in Redwood City and 96 degrees in Fremont.
The high temperatures recorded Tuesday were all expected to climb by a degree or three on Wednesday. Sarment said warmer-than-normal temperatures would also permeate cities closer to the water, but those cities would be significantly cooler than those inland.
A red flag warning for severe fire conditions also went into effect at 11 p.m. Monday in the East Bay Hills, Marin Coastal Range, Sonoma Coastal Range and the Santa Cruz Mountains. Forecasters said the temperature might reach 90 degrees amid wind gusts expected to be at least 25 mph. That alert was set to remain in effect through 11 p.m. Tuesday.
A wildfire in Napa County broke out north of Calistoga on Tuesday morning, according to authorities; the Toll Fire had consumed 50 acres as of about 2:20 p.m Tuesday. Evacuations were in effect south and east of the Lake County Highway and west of Palisades Road, as well as north of Old Lawley Toll, south of state Highway 29 at Oat Hill Road and east of Lake County Highway.
PG&E said fire danger created by winds and low humidity forced its hand, and the utility shut off power in parts of Napa, Solano, Lake, Yolo, Colusa, Shasta, Glen and Tehama counties.
The Bay Area Air Management District also extended Tuesday’s Spare the Air alert through Wednesday. The alert is the fourth one of 2024, and all of them have come since mid-June. Air quality officials said smoggy conditions could make the air unhealthy and hard to breathe for small children, infants, elderly people and those with heart and respiratory conditions.
The heat also brought a closure to many of the East Bay regional parks in Alameda and Contra Costa counties, though officials said that swim facilities and shoreline regional parks would remain open.
The soaring temperatures led Caltrain to restrict trains to 50 mph, down from the usual maximum speed of 79 mph, according to transit agency spokesperson Dan Lieberman. Half-hour delays were reported.
In the East Bay, Bay Area Rapid Transit was also running trains at slower speeds than normal due to the weather.
Bay Area counties prepared for the heat by making cooling centers available through at least Saturday, though many will be closed for Thursday’s Fourth of July holiday.
Forecasters and public safety officials also emphasized again the dangers of using fireworks, mostly illegal across the Bay Area. Fire officials said fireworks were suspected in a vegetation fire late Monday in the Oakland hills that burned two acres near Centennial Drive and Grizzly Peak. That fire did not threaten any homes, officials said.
“We really can’t emphasize enough how dangerous it’s going to be to use fireworks this year,” Sarment said. “Whether you’re in a red-flag area or not, just leave them alone. It’s a very dangerous idea.”
The heat was forecast to be the longest and hottest stretch for the region since the days surrounding Labor Day in 2022. The only “chilly” weather in the region on Tuesday was in Half Moon Bay, where the mercury was expected not to exceed 70.
Tuesday’s scorcher followed a Monday that normally would be considered a mini spike in the heat. Brentwood’s high temperature was 103, Concord reached 101, Morgan Hill got to 96 and San Jose 91. San Mateo’s high was 78, Oakland was 74 and San Francisco was 74, according to the weather service.
Sarment said that in addition to the heat, minor flooding created from tide anomalies could be an issue for some areas of coastal Marin County.
Staff writers Caelyn Pender and Jason Green contributed to this report.
Tips to beat the heat and prepare for power outages and wildfires
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- Bay Area heat wave: 5 ways to beat the heat during Fourth of July week
- How to stay safe, symptoms of heat stroke
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- How to check if your home will lose power during a public safety blackout
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- How to prepare and what to do when power is restored
- Wildfire evacuation checklist: Here’s what you need to pack before you must leave
- Map of California wildfires now burning
- Latest California fire updates and earlier stories
