FONTANA, Calif. - At least 40 hectares have burned in a wildfire that broke out Wednesday morning amid hot and gusty weather in San Bernardino County, east of Los Angeles.

The fire broke out in Fontana northwest of Interstate 15 at about 12:45 Wednesday, and winds near 50 kilometres per hour were pushing it west into the mountains and canyons of suburban Rancho Cucamonga, about 65 kilometres northeast of Los Angeles, county fire spokeswoman Angie Samayoa said.

People in about 100 homes near a Buddhist temple have been told they may want to evacuate but are not being ordered to do so, Assistant San Bernardino County Fire Marshall Mike Horton told KABC-TV.

"Homes are not directly in the line of fire," Samayoa said.

More than 300 firefighters were on the scene and water drops from aircraft were coming after sunrise, Samayoa said.

The fire broke out five years to the day after the beginning of the Grand Prix wildfire, which burned about 240 square kilometres and destroyed 135 homes in the same area, officials said.

Southern California was experiencing strong Santa Ana winds a week after similar conditions spurred several major wildfires.

The dry northeast winds were expected to peak at 80 kilometres per hour through Wednesday evening, but were expected to be weaker than last week's siege.

Temperatures will also reach the low 30s in many areas.