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.

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.