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.

Los Angeles County saw multiple wildfires erupt as "extremely critical fire weather" from dry conditions and Santa Ana winds threatened Southern California into Wednesday, and the National Weather Service warned the worst was yet to come.

The winds are common in California in the colder months, but they can sometimes help spread dangerous wildfires.