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

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 recent wildfires in Los Angeles were intensified by strong Santa Ana winds, which are a unique weather pattern in Southern California. These winds are caused by the topography of Southern California and the circulation of a strong high-pressure system over the Rocky Mountains.