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We’re still unclear about the exact causes of the fires, but one thing is certain – when they started, the weather and climate at that time created a devastating combination that allowed the flames to rapidly spread.
The initial issue is that Los Angeles has experienced extremely dry conditions. The city has received only 0.16 inches of rain since May 6, meaning the region’s rainy season has gotten off to a notably dry start. This has created a considerable amount of fuel for potential blazes. However, a shortage of rain alone did not lead to the catastrophic fires we saw this past week.
After the wildfires have burned out, what dangers will still be present in Southern California?
It was the wind that spread the flames quickly as soon as they were ignited. A powerful mountain wave wind event, with gusts of 80 to 100 miles per hour coming from the north, spread the fires faster than anyone could put a stop to them.
” extreme fire behavior and the winds are likely the strongest in Southern California since 2011.”
The December 1, 2011 event also brought very strong and damaging wind gusts to much of Southern California, including the Los Angeles metropolitan area.
According to the National Weather Service, wind gusts reaching speeds of up to 97 mph were recorded in the mountainous regions of northwestern Los Angeles County. However, unlike last week, no large wildfires occurred, unlike those in 2011. A normal rainfall from October to December of that year may have helped prevent a similar disaster from happening.
Typically, Santa Ana events are linked to northeast to east-northeast winds in Los Angeles County, and usually result in very little wind in the San Gabriel Valley and eastern San Fernando Valley regions, that are home to many highly populated parts of the LA metropolitan area.
During this recent event, the atmospheric conditions outside were directed from the north to northeast. This sent the strong winds directly over the San Gabriel Mountains, which allowed them to increase in strength and wind down the other side with even drier air. This brought intense wind gusts to areas that usually don’t experience winds of such force.
MORE: This has been the most disastrous fire the Pacific Palisades have ever experienced, according to specialists
What made this a devastating Santa Ana event was that conditions higher up in the atmosphere contributed to amplifying winds at the surface.
In this case, a low-pressure system in the upper atmosphere was moving over Baja California. The cold, heavy air linked to this system was moving in a north-northeast to northeast direction over the area. The particular pattern made it possible for the colder air farther up in the atmosphere to pour down to the ground and boost the winds already blowing down. This led to strong gusts sweeping across the Los Angeles and Ventura County Mountains, crashing into the foothills and some coastal communities.
The San Gabriel Mountains and the direction of the wind interacted to create a severe wind event, one that is relatively rare. The mountains also tend to make the winds more unpredictable due to the formation of additional whirls of air, referred to as wind eddies, as the air flows over the peaks and through the canyons.
While both the 2011 and 2025 events brought strong, damaging winds, one notable difference is the very low humidity in the LA area at this time.
We won’t know the full effect until studies are completed that determine how climate change contributed to the disaster. While climate change probably increased the severity of the factors that led to the devastating wildfires, it’s just one of many factors, including faster urbanization and land management practices, that played a role.
But we do know that wildfires in the Western United States have become bigger, more extreme and more devastating, and that human-enhanced climate change is one of the major factors contributing to this shift.
New studies reveal that climate change is making weather rollercoasters, where extreme dryness and intense wetness occur rapidly, happening more frequently.
California’s devastating wildfires were extremely challenging to contain.
A whiplash effect in California has led to a doubling of fire risk: first, it led to a significant surge in the growth of high-density flammable vegetation just before fire season, and then severely dried it out using extreme dryness and heat.
Less than a year ago, Los Angeles experienced historic flooding, and now the city is dealing with severe drought conditions, which actually makes the problem worse.
It’s crucial to emphasize that California’s susceptibility to wildfires will always exist because of its natural climate. The state is fundamentally shaped by highly variable and dynamic weather conditions, often experiencing significant shifts from extremely dry to extremely wet periods.
Across the continental United States, California experiences more variation in year-to-year moisture levels. As you move further south into Southern California, this variation becomes even more pronounced, according to Julie Kalansky, a climate scientist and deputy director of operations at the Center for Western Weather and Water Extremes at the University of California, San Diego’s Scripps Institution of Oceanography.
