The Santa Ana winds are dry, powerful winds that blow down the mountains toward the Southern California coast. The region sees about 10 Santa Ana wind events a year on average, typically occurring from fall into January. When conditions are dry, as they are right now, these winds can become a severe fire hazard.

In recent days, however, the region’s powerful Santa Ana winds—which have been fanning the flames—have begun to slow down. This lull has offered firefighters a reprieve and a key opportunity to make progress against the blazes, but forecasts suggest the Santa Ana will return next week. What are these gusts, and how have they become so strong?