NWS' 3:40 a.m. advisory indicates winds were blowing northeast at speeds between 25 to 35 mph, with gusts up to 60 mph.

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

Strong winds and power outages have prompted schools in East County to cancel classes for the fourth day in a row, while a major brush fire on Otay Mountain has also forced closures in Chula Vista.

The Border 2 Fire, a brush fire that erupted on Otay Mountain near the U.S.-Mexico border in San Diego County on Thursday afternoon, January 23, spread rapidly under a Red Flag Warning. RESTRICTIONS AND USAGE TERMS: Please credit “@kaayveee via Spectee”.

A red flag warning was set to expire for San Diego County Wednesday as Santa Ana winds diminish, although dry conditions could still create concern for wildfires in the days to come, forecasters said.

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

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.

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

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 Hughes, Sepulveda and Laguna fires are among the latest blazes for Southern California during a fourth consecutive day of red flag fire weather warnings.

Strong winds and power outages have prompted schools in East County to cancel classes for the fourth day in a row.