Meteorologists said there was a chance the winds would be as severe as those that fueled the Palisades and Eaton fires, but that different locations would likely be affected.

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?