Cooler temperatures and rain are possible in Southern California this weekend, but fire danger is increasing in areas already burning the state's largest wildfires this year.

The National Weather Service predicts scattered showers and thunderstorms are expected across the southern part of the state on Saturday, but cooler temperatures over the weekend may provide a temporary relief from the lingering heat wave gripping the region.

National Weather Service meteorologist John Dumas said fire danger may only increase despite expected rainy weather and cooler temperatures.

In a pattern called virga, moisture in the middle layers of the atmosphere falls as rain but evaporates before hitting the ground, Dumas said.

“Unfortunately, lightning can still reach us,” Dumas said, potentially sparking new wildfires.

That could make things worse for firefighters who are working around the clock to put out the blazes. Fire on the Lake California's largest fire so far this year has burned in Santa Barbara County, growing to 37,742 acres as firefighters work to contain the blaze in the Santa Ynez and Los Olivos areas, where properties are at risk.

Capt. Scott Safechuck, a spokesman for the Santa Barbara County Fire Department, said firefighters have made “visible changes” in recent days on the south side of the fire, where flames were previously visible from the Santa Ynez and Cachuma Lake areas.

Firefighters worked through the night to put out the blaze by burning dry vegetation and dropping water from helicopters, a coordinated effort that “has been really successful in eliminating much of the threat on the south side,” Safechuck said.

The risk of dry lightning causing fires has led weather officials to Red Flag Warning Snow is expected to continue through 9 p.m. Saturday in the mountains and foothills of Los Angeles County, the Antelope Valley, valleys in San Luis Obispo and Santa Barbara counties, and Ojai and Casitas Valleys, according to the weather service.

Dumas said weather service officials have tools that allow them to track lightning in real time and model the probability of lightning striking, which helps firefighters on the ground.

Dumas also said temperatures would drop by a degree or two over the next few days, returning to “near-normal temperatures” by Monday or Tuesday before a new heat wave hits Southern California.