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.

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.

A critical fire threat will continue across County as Santa Ana winds and dry conditions persist through early Friday, according to the National Weather Service.

After a weekend of reprieve allowing fire teams to continue making progress battling the deadly infernos burning in Los Angeles County, Southern California now faces another round of fire-fueling Santa Ana Winds Monday.

San Diego County remains under the grip of another round of moderate to strong Santa Ana winds, paired with extremely dry air, elevating critical fire weather concerns.

Not only do these winds accelerate the speed and spread of the fires, they also affect how the fires are fought. The strong winds can make it dangerous to fly aircraft used for containing the fires.

Much of inland San Diego County was whipped yet again by a strong Santa Ana wind event Monday into Tuesday, contributing to risky fire conditions as the region remains bone-dry.

Since Jan. 8, one wave after another of fierce Santa Anas have blown through Southern California. Thus far, the San Diego area has escaped the devastation seen in the Los Angeles areas by wind-whipped blazes that leveled homes and forced evacuations.

The National Weather Service issued its highest fire weather alert level for portions of the Los Angeles area for Monday into Tuesday morning, as powerful Santa Ana winds return. Threat level: The "Particularly Dangerous Situation" Red Flag Warning indicates any fires that ignite could quickly grow out of control.

The stiff Santa Ana winds that stoked a short-lived but dangerous wildfire Monday in Poway were expected to be flat-out wicked before dawn Tuesday in San Diego’s backcountry, where something as minor as the heat from a car muffler could spark a major blaze,

This week, the Santa Ana winds are expected to hit the region, possibly sparking more fires in Los Angeles, Orange, Riverside, San Bernardino and/or Ventura counties. The National Weather Service declared a rare PDS, or "particularly dangerous situation," red flag warning for the Los Angeles area ahead of this week.