"If fire ignition occurs, conditions are favorable for rapid fire spread and extreme fire behavior," the NWS said.​

A Red Flag Warning that went into effect Monday for San Diego County mountains and valleys has been extended due to strong gusty winds and low relative humidity.

High fire danger warnings have been a recurring theme for Los Angeles in January. Here's a look at how many red flag warnings were issued this month.

The National Weather Service has extended a Red Flag Warning until Friday morning for San Diego County's inland valleys and mountains.

A Red Flag Warning remained active for inland and mountain communities through Friday morning, which means it could be another busy day for local fire crews.

Another blast of Santa Ana winds Thursday prompted San Diego Gas & Electric to cut off electricity to thousands of residents in another of a wave of power outages that have continued off and on for two weeks.

The National Weather Service issued red flag warnings until Friday morning for inland valleys and mountain areas.

"A Red Flag Warning means that critical fire weather conditions are either occurring now, or will shortly," the NWS said.

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.

"If fire ignition occurs, conditions are favorable for very rapid fire spread and extreme fire behavior," the NWS warns.

A fire broke out Wednesday night along the 405 Freeway in the Sepulveda Pass near the Getty Center, burning about 20 acres and spurring an evacuation warning.