Extreme fire weather returns to Southern California - particularly Los Angeles and Ventura counties - as winds of up to 100 mph have prompted the most urgent warning from the National Weather Service.

Santa Ana winds occur when air flows west from a region of high pressure over the dry Great Basin to lower pressure off the California coast, According to Accuweather. As that cool interior air flows over and through mountain passes, it accelerates, sinks and compresses.

One of the biggest stories of 2025 thus far has been the wildfires in California. A common occurrence in that state, wildfires are often fueled by a combination of drought and terrain. The terrain allows for the development of Santa Ana winds that cause any fire to spread very quickly.

A second day of ferocious winds were forecast for Tuesday in Southern California where firefighters remained on alert and extreme fire weather raised the risk of new wildfires two weeks after two major blazes still burning in the Los Angeles area sparked.

Santa Ana winds can occur when the pressure gradient caused by a high-pressure region over the Rockies, in combination with friction, forces air from the mountainous West down the San Gabriel Mountains in southern California.

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.

Santa Ana winds are whipping Southern California on Tuesday, sparking fresh fears that progress made fighting wildfires that have scorched over 40,000 acres and left 27 dead could be reversed and more blazes could break out.