Tens of thousands of people have fled their homes as a brush fire in the Pacific Palisades has grown to nearly 20,000 acres on Thursday.

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.

Santa Ana winds are caused by strong high pressure over the Great Basin region of the West creating a pressure gradient that amps up winds through the mountains, foothills and sometimes valleys of Southern California. In this case, the winds are getting a major boost from a strong upper-level low pushing southward across the state.

At least five wildfires are ravaging Southern California, and the three largest have already killed at least five people, burned tens of thousands of acres and prompted the evacuation of an estimated 179,

With multiple wildfires and high winds impacting the greater Los Angeles area and other parts of southern California, local airports and many common tourist destinations are affected.