Southern California will continue to face "dangerous fire weather conditions" including strong Santa Ana winds and extremely low humidity through later this week, forecasters said Tuesday.

As winds across the Southern California area are calmer than their peak and firefighters are making progress, the threat to the fire-weary region remains with Santa Ana winds expected to continue in the coming days.

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.