Millions of California residents were placed under a red flag warning through Thursday amid threats of further fires with looming winds in the forecast, according to multiple reports.

The Santa Anas are expected to be most powerful Monday night into Tuesday. Fire services across the region say they are ready.

The Santa Ana winds fanning wildfires that have killed at least 25 people in Southern California and destroyed more than 10,000 houses, businesses and other structures in Greater Los Angeles are flaring up again.

A wind-driven wildfire charred dozens of acres in the sparsely developed northeastern reaches of San Diego County, damaging structures and forcing pre-dawn evacuations before crews could gain the upper hand on the flames Wednesday.

With the strongest gusts expected on Tuesday, extreme fire condition threats will prevail until midweek, L.A.-area fire chiefs say.