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

The San Fernando and San Gabriel valleys are expected to see winds at 30 to 50 mph until Wednesday evening, with widespread gusts even higher, weather officials said

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.