The deadly Eaton Fire in Altadena and Pasadena is 45% contained Wednesday, while red flag warnings of critical fire danger will be in place over the burn area — and much of the Southland — through 6 p.

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.