LOS ANGELES – The National Weather Service office in Los Angeles warns that Santa Ana winds will bring the “highest possible” fire danger to most of Los Angeles and Ventura counties in Southern California.

These winds are expected to increase Monday evening and continue into Wednesday evening.

The NWS has issued a Particularly Dangerous Situation (PDS) fire weather warning through Tuesday for much of the Santa Ana Wind Corridor in Los Angeles and Ventura counties. The PDS warning is in effect for the Susana Mountains until Wednesday. Further south, San Diego County is also under a fire weather warning.

Forecasters at the NWS Los Angeles office noted that these fire weather conditions “could rival other recent historic fires,” including the Mountain Fire last month and the Thomas Fire in December 2017.

The Ventura County mountain fire quickly grew to nearly 20,000 acres and destroyed nearly 250 homes and buildings in early November.

Santa Ana winds blow from the Santa Ana Mountains in Southern California, bringing hot, dry air from the east of the mountains. They can occur at any time of the year, but are more common in cooler weather from fall to winter.

WHAT IS A RED FLAG WARNING?

Many of these counties’ windier corridors could experience damaging wind gusts that could cause trees and power lines to fall, as well as power outages.

San Diego Gas & Electric alerted customers via social media that the utility could turn off power depending on wind conditions to prevent possible fires from downed power lines.

CAL Fire Public Information Officer Mike Cornett told local media that people in warning areas must be prepared to leave at any time.

Santa Ana winds can often increase the fire danger for Southern California, and forecasters expect that to happen this week.

“This event has the potential to be as strong as the Santa Ana event on November 5-6 that led to the Mountain Fire,” warned the NWS Los Angeles. “Prepare for fire weather by ensuring you have defensible space and creating an evacuation plan. Any new fire will grow rapidly and will likely exhibit extreme fire behavior.”

The greatest fire danger is late Monday night through Wednesday. NOAA’s Storm Prediction Center is forecasting “extreme” fire weather conditions Tuesday in places like Santa Clarita, Thousand Oaks, Simi Valley, Moorpark and Santa Paula along the Southern California coast.

NWS forecasters said the fire danger will be heightened through Wednesday by an overlap of relative humidity levels dipping into the single digits and damaging wind gusts between 60 and 80 mph.

SATELLITE IMAGES REVEAL THE EXTENT OF MOUNTAIN FIRE DEVASTATION IN CALIFORNIA

Given the forecast conditions, the Los Angeles Fire Department (LAFD) is asking people not to use spark-generating devices outdoors this week.

“If you must, make sure you have enough water on hand to extinguish any sparks before it is too late,” LAFD wrote on Facebook.

The FOX Forecast Center noted that unlike typical Santa Ana winds, this event “will have a more easterly direction, which could bring stronger gusts to areas where they do not normally occur.”

This wind direction could also create dangerous conditions in Avalon Harbor with strong winds and rough waves.

In the mountains on Tuesday, wind gusts could reach 70 mph and relative humidity will be between 5% and 10%.

The wind will die down by Wednesday afternoon. However, the humidity remains extremely low.