While Christmas carols full of cheer may soon fill the airwaves, the December air will bring a heightened danger of fire all week, meteorologists say.

Santa Ana winds accompanied by low relative humidity and relatively high temperatures will cover much of Southern California through the end of the week, said Brett Albright, a meteorologist with the National Weather Service’s San Diego office, which covers the Inland region and Orange County.

In those areas, a red flag warning — meaning an elevated fire danger — is in effect early Monday morning through Thursday evening, according to a weather service forecast.

“We’re going to be looking at critical fire weather conditions starting Monday and continuing through the week. It’s going to be a prolonged event,” Albright said Saturday, Dec. 2. “If something goes up, it’s going to be tough for firefighters, because they won’t get any relief during the day or the night for five, six days.”

It’s unusual for fire season to extend this late, but there hasn’t been a substantial rain in months, Albright said.

Similar conditions are expected in Los Angeles County, said Kathy Hoxsie, of the National Weather Service’s Oxnard offices, which has responsibility for the parts of Southern California not covered by the San Diego office.

“I don’t know that I would go as far as to say red flag warning, but it will be warm, dry and breezy,” Hoxsie said. “Especially on Tuesday — that looks like it will be the strongest day.”

The National Weather Service advises people to keep their vehicles off dry grass, avoid activities with open flames or sparks and otherwise be careful of fire danger.

The winds could also be strong enough to knock down trees and affect drivers below the Cajon Pass along the 15 and 210 freeways, Albright said.

People with respiratory problems might also be affected by the low humidity, he added.

High temperatures are forecast to be generally in the 60s for the Inland Empire and in the 70s in Orange County, San Fernando Valley and South Bay.

“It’s not going to be a particularly warm Santa Ana event,” Albright said. “It’ll be above average but not like it was a week ago. It’s a December heat.”