LOS ANGELES — School’s been in session for weeks. Football season is well underway. Everything is autumnal in California except the weather.

A heat wave with triple digits is expected to hit Los Angeles area, the San Joaquin Valley and Sacramento on Saturday.

The San Francisco Bay Area was expected to see weekend sunshine and temperatures in the 70s and 80s.

High winds were expected along with the high mercury, and fire danger because of both.

Strong gusts up to 55 mph (89 kph) were expected into the weekend from Monterey south to San Diego, according to the National Weather Service.

Red flag warnings for high fire danger were issued in mountain and valley areas into Sunday, as forecasters predicted humidity levels could slip below 15 percent.

Fall often brings high fire danger to Southern California because of seasonal winds. Several years of drought have further heightened the flammability of brush.

“Traditionally, late September through mid-November is Santa Ana season,” Cal Fire Chief Thom Porter said. “Many of the state’s largest and most damaging wildfires coincide with this time of year.”

Longtime Pasadena resident Mona Teebay said she notices it every fall.

“The fire kind of affects your life,” the 57-year-old woman said. “You always have fall activities disrupted.”

Teebay said she believes poor air quality exacerbated by smoke from nearby wildfires caused her 23-year-old daughter to develop asthma as a baby.

And wildfires often forced her daughter’s summer camps to be cancelled, she said.

Some communities stationed additional fire crews in danger areas to deal with the increased risk.