Temperatures approached triple digits in much of California on Saturday afternoon and surpassed 100 degrees in inland areas as a steaming autumn in the state seemed more like an endless summer.

Heat in the 90s was felt in the normally temperate San Francisco Bay Area, where temperature records were expected to fall before the day was over.

Throngs of thousands who crammed Golden Gate Park for the annual Hardly Strictly Bluegrass festival were chugging water and dumping it on their heads as they danced to banjos and fiddles in the midday swelter, with many wearing shorts and little else.

Heat in the Sacramento also pushed well into the 90s.

The mercury was at 95 degrees in downtown Los Angeles by midday and 101 in the suburbs of San Bernardino County.

Normally closed for the season by now, the Raging Waters theme park in San Dimas, where it was 97 degrees Saturday afternoon, was open to provide relief and recreation for another weekend.

A high-pressure system extending over the western part of the country, along with Santa Ana winds that blow across deserts and down mountain canyons before arriving in Southern California, are generating the sweltering conditions.

The heat brought a red-flag warning of critical wildfire conditions through Saturday night, the National Weather Service said.

The U.S. Forest Service has implemented 24-hour firefighter staffing. The Los Angeles County Fire Department has beefed up many of its firefighting crews from three to four people and stationed extra equipment in strategic locations.

"We've got wind, heat, the perfect combination, everything in alignment for a potential brushfire," fire Capt. Rich Moody said as he and his crew patrolled a Southern California hillside.

Meanwhile, the Los Angeles Department of Water and Power is urging people to set thermostats at 78 degrees.