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.

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.

The Los Angeles region, still reeling from this month’s firestorm, is under a red-flag warning from noon Monday through Tuesday morning.