Santa Ana winds: facts and fiction
As Southern California braces for more rounds of Santa Ana Winds, we dive into the facts and also some mythology about them.
Windy weather is leading to an extreme risk of wildfires in Southern California this week.
The Santa Ana winds of Southern California can be visualized in several ways. You can see their effects as palm trees sway in the morning light or when clean-up crews arrive to deal with branches and debris on streets. Woe unto any Angeleno who doesn't keep their car indoors – as objects large and small end up on vehicles, with alarms going off wildly in the night.
Santa Ana winds bring distinct weather to Southern California. Observing weather data, clues of past wind events are immediately clear. Nov. 12, 2023, Hawthorne, California: High 83F, with a bone-dry humidity recording of 9%. Nov. 14, 2021, Burbank, California: A scorching high of 92F with humidity again in the single digits.
Santa Ana winds occur when winds blow and pick up speed as they travel from the inland deserts toward the coast. These wind events usually kick off in the fall and winter months in the Los Angeles area, coinciding with Southern California's notorious fire season.
After a low pressure system passed through the Bay Area on Monday to bring precipitation to the Bay Area and cooler weather to Southern California, moderate northerly winds impacted Los Angeles and San Diego areas on Tuesday, raising temperatures in some areas and drying things out. Today is forecast to be the warmest day of the week in Los Angeles, with high temperatures expected to be back in the upper 70s near Downtown Los Angeles.
But while Angelenos might enjoy the warmer and drier weather during these wind events, all it takes is an unattended campfire or a cigarette to spark a massive wildfire in environments where land is already parched having not received any rain since the spring in some cases.
From small animals becoming conductors of electricity to gender reveal parties to sparks from a lawnmower and more, here are some of the most surprising ways wildfires have been started.
As the region braces for more inevitable rounds of Santa Anas during the fall and winter, here are a few facts, and also some myths, about them.
Santa Ana winds aren't always warm
Santa Ana winds and, their Bay Area cousin, the Diablo winds occur when air from a region of high pressure over the dry Great Basin region of the U.S. flows westward toward lower pressure located off the California coast. Remember that air generally wants to flow from higher pressure to lower pressure. As that cool interior air flows over and through mountain passes, it accelerates, sinks and compresses. When you take this dry air and cause it to flow downhill to the lower elevations, the temperature rises as the air descends.
Think of the flow of air much like the flow of water, AccuWeather Meteorologist Dave Houk explained.
"If you think of the mountains as rocks jutting up in a stream or river, that barrier blocks the water flow and causes the flow to accelerate around the rock," Houk said. "This is the same basic physics that governs the acceleration of the air through the gaps and canyons down to the coast."
But while we often think of these winds as ushering in warmer weather, causing even some January days to soar into the 80s in L.A., this isn't always the case. The warm and cold flavors of Santa Ana winds are generally rooted in the same dynamics. But cold Santa Ana wind events, Houk said, are driven by mid- and upper-level low pressure and colder air aloft. "These mid- and upper-level low pressure areas are typically what produce the majority of fall and winter precipitation events over the Southwest and snow in the Great Basin," Houk explained. This limits how much warming the air can undergo as it tumbles down from the mountains to the coast.
Most importantly, with both flavors, you still need these winds to line up flowing from the northeast into Southern California for a Santa Ana event.
Powerful winds
(Photo credit: Getty Images)
Those who have not experienced Santa Ana winds might not appreciate how strong they can be. In March 2024 after a cold storm coming from the Great Basin, the mountains near Santa Clarita recorded an 86-mph gust, Rancho Cucamonga reached 82 mph and Arrowhead Springs had an 87-mph gust, according to the National Weather Service.
An even more vicious Santa Ana setup happened in early December 2011, with a peak gust of 97 mph at Whitaker Peak, winds commonly found in a Category 2 hurricane. These devastating winds toppled thousands of trees, knocking out power for over a week. Schools were closed, airplanes were diverted and Pasadena declared a state of emergency.
Southern California is prone to wildfires significantly during the fall season and it’s due to the presence of Santa Ana winds.
They make your mood change and skin crawl
There's the science of Santa Ana winds and then the mythology as these winds weave in and out of Southern California memory. "There was a desert wind blowing that night. It was one of those hot, dry Santa Anas that come down through the mountain passes and curl your hair and make your nerves jump and your skin itch," wrote Raymond Chandler in "Red Wind: A Collection of Short Stories."
A 1988 Los Angeles Times article claims that the Santa Ana winds “contain an excess of positive ions," leading to complaints of more headaches, nausea and changes in mood, but there isn't any real data to support this.
As the Santa Ana winds continue to howl like clockwork every year across Southern California, expect the real and imagined impact of them to continue. What else can you expect in Hollywood's backyard?
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