Expect the ‘strongest and longest’ Santa Ana winds of the season this week in L.A. area

Deflate your giant Santas and unplug those twinkly holiday lights: The Santa Ana winds are coming to town.

Authorities anticipate high fire risk with a red flag warning in effect through Thursday — Los Angeles and Ventura counties could see wind gusts between 50 and 70 mph Monday night into Tuesday, the National Weather Service predicts.

“This will likely be the strongest and longest duration Santa Ana wind event we have seen so far this season,” the National Weather Service red flag warning reads. “If fire ignition occurs, there will be the potential for very rapid fire spread, long range spotting, and extreme fire behavior.”

Sustained winds around 30 mph will likely begin around 10 p.m. Monday, said National Weather Service meteorologist John Dumas. Temperatures this week could reach from the high 70s to low 80s — that’s lower than normal for Santa Ana conditions, but higher than usual for this time of year in Los Angeles, Dumas said.

Infographic: Where do the Santa Ana winds come from? »

The lower temperatures may help avoid fires. But if winds knock down a power line and ignite flames, Dumas said, the fire “could spread rapidly because of the wind condition.”

Southern California has also seen less rain than usual so far this season, Dumas said, which creates fire conditions. Downtown L.A. should have seen about two inches of rain between October and now. There has been a tenth of an inch of rain, he said.

Beyond the perennial fire safety measures that authorities recommend — don’t pull over in dry grass, be careful with anything that could cause sparks outside — the holiday season could pose an added risk, Dumas said.

“What concerns me most would be all of the people who have been doing their holiday decorations. Generally you’re not anticipating a big wind storm when you’re putting things out,” Dumas said.

Beware of stringing lights outside the house and through trees this week, Dumas said. Tonight might be a good night to keep those unplugged, to lower the chances of them igniting flames.

“My advice is if you’ve got the big inflatable Santa in your front yard you probably don’t want to inflate it this evening,” Dumas said. “It’ll just blow away.”

Reach Sonali Kohli at Sonali.Kohli@latimes.com or on Twitter @Sonali_Kohli.