SAN FRANCISCO (CBS/AP) -- The Bay Area and the entire state of California were preparing Thursday for a scorching weekend that could see temperatures hit triple-digit highs in many areas, even above 5,000 feet in the mountains, as a massive heat wave rolls through the West Coast.
Excessive-heat advisories starting during the weekend were issued for interior valleys of the San Francisco Bay and Monterey Bay region, where highs are expected to range from the 90s to 105.
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The National Weather Service also posted excessive-heat watches for the 450-mile length of the Central Valley from Bakersfield north to Redding, and issued excessive-heat warnings through Sunday night for areas from Santa Barbara County south to the Mexican border. Forecasters expected temperatures to hit 120 in the deserts.
Experts warned people to stay out of the sun, wear broad-brimmed hats outdoors, drink lots of water and avoid putting pets and children in parked cars where the temperature can quickly soar. Drivers who might find themselves stuck in a hot car should carry extra sunglasses, water, snacks and any prescription medications they may need, emergency management officials advised.
It was anticipated that many communities will designated air-conditioned libraries or community buildings as cooling centers to provide relief, especially for children, the elderly and people with medical conditions that might make them more susceptible to heat illnesses.
The hottest temperatures were expected on Saturday and Sunday before beginning to ease, but it still will be above-average through Tuesday, said KPIX 5 meteorologist Brian Hackney.
A huge high pressure system, not seen by Californians for several years - probably the mid- to late 2000s, was centered over New Mexico but was moving westward. The pressure causes air to sink and warm, drawing down humidity. As the air warms, it can hold more moisture, and that takes out the clouds.
The California Independent System Operator, which runs the state's power grid, expected to cope with any surge in demand from the heat.
Demand usually drops on weekends as office buildings and some manufacturers shut down, and if there's a surge, the system can bring more generators online and call a Flex Alert, where some customers voluntarily reduce their usage, spokesman Steven Greenlee said.
"We've been preparing all year for the summer," he said. "At least for the short term ... it looks like we're going to be OK."
However, Greenlee said the long-range forecast is for above-average temperatures through August. The grid also could be stressed in case of a disaster.
"All we need is another big wildfire or two that's going to take transmissions lines out," he said. "That's the risk that all of a sudden can turn not very good pretty fast."
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