Strong Santa Ana winds are hitting fire-ravaged Los Angeles on Friday morning, but the winds will relax later in the day and the red flag warning will end Friday night.

Santa Ana winds are common in Southern California during cooler months. Here’s a look at the often-fierce winds that topple power lines and trees and can turn a spark into a raging wildfire.

Red Flag Warnings remain in effect through Friday evening for much of Los Angeles and Ventura Counties, the National Weather Service said.

Powerful Santa Ana winds are set to pick up again, making it challenging for firefighters to gain control of the severe wildfires in southern California. Meanwhile, a winter storm is bringing cold temperatures,

The devastating fires that have killed at least five people and forced the evacuations of tens of thousands of residents across the Los Angeles region are driven by Santa Ana winds that blow from the deserts of interior California and Nevada out to the Pacific Ocean.

The nature of the Santa Ana winds makes them perfectly suited to fueling blazes like the Palisades Fire, and climate change is increasing the risk

The Palisades, Eaton, and Hurst fires covered more than 5,600 acres of Southern California as of Wednesday morning. Tens of thousands were under mandatory evacuation orders but the fires increased in size overnight, helped by the blustery Santa Ana winds.

By the time the winds get to the point where the Eaton Fire broke out in Altadena on Jan. 7, it’s not uncommon for them to have less than 5 percent relative humidity, meaning essentially no moisture at all.