Although the strongest wind gusts have passed through the Southern California region, another "traditional Santa Ana wind event" will move in Thursday night.

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.

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

Jon Keeley, a research ecologist in California with the U.S. Geological Survey and adjunct professor at UCLA, explains what causes extreme winds like this in Southern California, and why they create such a dangerous fire risk.

With winds roaring as high as 80 miles an hour in places such as Palomar Mountain, SDG&E earlier this week initiated Public Safety Power Shutoffs that de-energize circuits in areas to help ensure that gusts don’t knock down power lines and possibly start a fire when they hit the ground.

The Santa Ana winds are blustery, dry, and warm and can result in massive damage. These winds could boost the danger of a wind-driven fire if they occur during wildfire season. Three major wildfires in the Los Angeles area are being driven by one of the most powerful Santa Ana winds in years.

The Palisades, Eaton and Hurst wildfires raging in Southern California will be fueled by peak winds of 100 mph, placing 19 million people at risk. NBC News meteorologist Angie Lassman has the details on Early Today.