The old Bay Area adage -- If you don’t like the weather just drive 10 miles in another direction -- was in full force Wednesday.

While it was a chilly 53 degrees at Fort Funston in San Francisco at 1:30 p.m., just 30 miles to the east in Livermore it was 103 degrees.

“You don’t want to sit in the house and run the air conditioning all day long,” Sarah Nelson told KTVU as her children enjoyed the waters of Shadow Cliffs Regional Recreation Area in Pleasanton. “So I thought it would be good to come out here and enjoy the water before it gets too hot.”

Carolyn Nakamoto came to the park from Sunnyvale with 10 children in tow.

“They (the children) love it here,” she told KTVU. “It’s one of their favorite places to be (on a hot day).”

The soaring temperatures in the inland Bay Area cities triggered an 'Spare the Air' alert for the second straight day.

The Bay Area Air Quality Management District issues the alert when ozone pollution reaches unhealthy levels. The district was asking local residents to car pool or take public transportation if possible, refrain from using gas-powered lawn mowers and not to use their charcoal barbeque grills. To get additional information and sign up for Spare the Air AirAlerts, check the BAAQMD website.

Pacific Gas and Electric also issued an alert asking local customers to conserve power between 4 p.m. and 7 p.m. Wednesday. Customers can get additional information at the FlexAlert.org website.

While the microclimates in the Bay Area has residents either reaching for a jacket or a beach towel, Southern Californians baked under sweltering conditions.

As a high-pressure system lingered high over the Southwest, the mercury passed 80 before noon in downtown Los Angeles and the National Weather Service predicted highs of up to 108 in the Santa Clarita Valley, a bedroom community north of the city.

Deserts and mountains also could roast through Thursday, with highs past the century mark expected in some inland and valley areas from Los Angeles to San Diego County and highs of 110 to 118 in the lower deserts.

"This weather could be deadly for unprepared campers or hikers," the weather service warned in a forecast.

At the same time, higher humidity was bringing a chance of thunderstorms and dry lightning to the mountains and deserts during afternoon and evening hours through Thursday, creating a danger of fires. The arrival of hot weather this week prompted rangers in the Angeles National Forest near Los Angeles to raise the fire danger advisory to very high.

Electrical demand was up as people hiked up the air conditioning but not enough to kick-start conservation plans or require utilities to call on reserve supplies.

"So far, so good," said Stephanie McCorkle, a spokeswoman for the California Independent System Operator Corp., which manages the state power grid.

The corporation, known as Cal-ISO, recently unveiled plans to deal with summer weather and the loss of the San Onofre nuclear power station, whose two reactors have been shut down for repairs.

New transmission lines, the restarting of retired generators at a Huntington Beach plant and a conservation notification system were in place before the start of the season's first heat wave this week, spokeswoman Stephanie McCorkle said.

It hasn't been necessary to call on reserves or for major conservation efforts, although it might become necessary if the state is hit with back-to-back heat waves, a power plant shuts down or a wildfire knocks out a power line, she said.

"Electricity's not something you can bottle up and store on the shelf," she said. "We don't bring on more resources than we need. We have to have a cushion at all times in case we lose a plant or a power line."

Southern California Edison, which covers a huge area of the state that includes some of its desert areas, hasn't needed to activate its conservation plans "or even come close to it," spokesman Dan Chung said.

The same was true for the Los Angeles Department of Water and Power, which can call on supplies from power plants, solar and wind sources as far away as Arizona.

In San Diego County, the recently completed $2 billion Sunrise Powerlink transmission line can provide 40 percent more imported electricity to the eastern county if needed, said Allison Zaragoza, spokeswoman for San Diego Gas & Electric.

So far, it hasn't been necessary, she said.

Despite the inland swelter, temperatures dropped off dramatically in coastal cities, where many beaches were cloaked in an unseasonal blanket of "June gloom"-style fog.