It's almost December, typically a time of regular rainstorms and mountain snows in California. But instead, millions of people from the Los Angeles area to San Diego are experiencing a dangerous Santa Ana wind event that is raising fire risks to "critical" levels, the second-highest threat category.
Red flag warnings along with warnings and advisories for high winds are in effect for downtown LA and inland areas of San Diego counties, with wind gusts so far exceeding 80 mph in some mountain areas. Santa Ana winds are expected to continue to whip across the region through today, sending air moving from inland areas to the sea. As the air descends from the mountains, it compresses and dries out, leading to extremely low relative humidity levels, in the single digits in some areas.
So far, no major wildfires have ignited during this event, though several small fires have broken out in Southern California.
According to the Weather Service, the cause of this offshore wind event is a low-pressure area diving into the Great Basin. The air circulation around this feature is powering winds through mountain passes and up and over high terrain toward heavily populated areas of the state.
Typically, California's biggest firestorms have occurred during periods of strong offshore winds such as this one. In an effort to prevent sparks from triggering any fires, Southern California Edison, the area's biggest utility, is warning more than 100,000 customers that they may lose power as a preventive measure. Most of the customers are in LA and San Bernardino counties.
The 2020 wildfire season in California has been unrelenting because of record warmth, a deepening drought, an abundance of lightning strikes and extreme offshore wind events.
Santa Ana winds resulted in major fires in Orange County in late October, forcing tens of thousands to evacuate on short notice. Now, though, vegetation is even drier because of the lack of significant rainfall, which makes the strong winds riskier.
The months of August, September and October each ranked as the state's hottest since records began in 1895.
Without enough rain, high fire danger is continuing into November and December in Southern California, and the driest period is now coinciding with the windiest. Many lower-elevation locations, along with the mountains of Los Angeles and Ventura counties, have received less than a quarter inch of rain since Oct. 1, which marks the start of the water year in the state.
And there are no significant rains in sight for Southern California.
California is in the midst of its worst wildfire season on record, with about 4.2 million acres burned, more than double the acreage in the previous record-breaking year. At least 10,488 structures have been destroyed and 31 people killed. Five of the top six largest fires on record in the state have occurred this season.
Information for this article was contributed by Diana Leonard of The Washington Post.