An unusually intense high-wind event is underway in California, knocking down trees and power lines and contributing to “critical” wildfire risk to much of the state stretching from Lake Tahoe to San Francisco southward to Los Angeles and San Diego. Although it’s midwinter, which is typically the rainy season in the Golden State, wildfire risks have spiked to “critical” levels in Southern California after a period of dry, record warm weather dried out vegetation.

Multiple wildfires have ignited in Northern and Southern California, including some near the locations of the large blazes that raged last summer and fall.

Any fire that ignites between Tuesday and Wednesday amid the windstorm could spread rapidly and exhibit “extreme fire behavior,” the National Weather Service forecast office in Los Angeles warned. Utility companies in Northern and Southern California have preemptively cut power to thousands in an effort to avoid having their equipment light a deadly blaze, as has happened in recent years.

Southern California Edison, the main utility serving the L.A. metro area, is considering cutting power to about 270,000 customers, depending on how the situation unfolds.

Already, gusts of wind in Northern California have increased, with a gust to 64 mph recorded in Oakland near daybreak local time, while locations in the Sierra Nevada mountains saw winds at the summits whipping at more than 100 mph. Yosemite National Park is closed due to the high winds and associated damage to trees and park infrastructure. In the L.A. area, the highest gust has been 95 mph, recorded in the hills above Ventura, Calif.

According to PowerOutage.us, about 270,000 customers are without power across California due to the high winds, a number expected to grow throughout the day.

The culprits for the strong winds are two low-pressure areas, which are swirls of counterclockwise circulating air, sliding from north to south across Central and Southern California. Accompanied by strong winds in the mid-levels of the atmosphere, these lows are combining and taking up residence over the Pacific to the southwest of Los Angeles.

Meanwhile, high-pressure building into the Great Basin is yielding a tight contrast in air pressure across the Southwest. Since air flows from high to low pressure (in an ultimately futile attempt to equalize pressure differences), this creates a rapid flow of air from land to sea through California, generating what are known as Santa Ana winds.

Some of the strongest winds in the area are expected in the higher elevations of Los Angeles and Ventura counties, where the topography will help accelerate wind speeds to as high as 90 mph, according to the Weather Service. However, even downtown Los Angeles could see winds gusting to 60 mph at times on Tuesday and into the night.

For a region already dealing with a devastating coronavirus pandemic and widespread stay-at-home orders, power outages — both planned and storm damage-related — could be even more disruptive than usual.

Rare January wildfire threat

The L.A. metro area is under a red flag warning for critical fire weather conditions, due to a combination of high winds, warm temperature and low humidity. This is the second-worst category of fire weather risk. While January is typically not wildfire season, there is a history of large blazes occurring during Santa Ana wind events such as this one. In addition, vegetation in Southern California is unusually dry right now, since this weather system is striking right after a heat wave set record high temperatures.

Now, temperatures are much lower, as this wind event is bringing cooler air, and this might help mitigate the fire risk. Humidity levels are slightly above what is typically seen in a critical fire risk event, but the winds plus the dry vegetation are enough to justify the risk category, the Weather Service said in an online forecast discussion.

There’s even a considerable wildfire risk in parts of wetter Northern California, which has seen more rain and mountain snow but not much precipitation in the past couple of weeks. Due to the strong winds and fire threat, Pacific Gas & Electric, which has been blamed for some of the state’s deadliest and most destructive fires in the past several years, has implemented rare midwinter preemptive power cutoffs in some parts of Northern California.

The devastating 2020 wildfire season, which was the worst in state history, has simply continued into 2021, much as the coronavirus pandemic has. Significant and steady rounds of precipitation are needed to alleviate deepening drought conditions across the state and avoid more fires.

Studies show that climate change is lengthening the fire season and creating larger blazes than would otherwise occur. The 2018 National Climate Assessment, published by the Trump administration, projected that those trends will probably continue for several decades.