Parts of Southern California will be hit by a long-lasting, most damaging storm of winds Tuesday through Thursday, January 6-8. The wind itself can wreak havoc, blowing down trees, branches and power lines. The bigger concern is fire: Fierce wind gusts will burn dry land brought about by one of the driest water years in Southern California history, so the spread of any wildfire could be devastating.
As of noon Tuesday, Magic Mountain north of the San Fernando Valley had recorded wind gusts of 84 mph, and gusts of 50 to 70 mph had become common. A fast-moving fire broke out over Pacific Palisades in the late morning and quickly grew to 200 acres before noon PST.
Winds could reach 60 mph in Pasadena and gusts in the mountains could reach 80 mph. @NWSLosAngeles pic.twitter.com/f9d6VCi9qD
— Edgar McGregor (@edgarrmcgregor) January 7, 2025
The worst could come late Tuesday and Wednesday, when “extremely severe” fire weather could occur in parts of Ventura and northern Los Angeles counties, according to the NOAA/National Weather Service The highest level of fire weather conditions issued by the Bureau of Storm Prediction Center.
Communities most at risk for fire weather are on the north side of the San Fernando Valley and adjacent higher areas, including Santa Clarita, Simi Valley, Moorpark, San Fernando and La Cañada Flintridge.
Critical fire weather conditions – just one level below “extremely critical” – will expand to a wider area, potentially affecting millions of people from the greater Los Angeles area to the San Diego area and the Inland Empire. Widespread wind gusts of 50 to 80 mph will extend to the coast in some areas, especially north of Los Angeles, where gusts could reach 100 mph in the mountains and foothills.
“Given the strength of the winds, extreme fire behavior is possible if fires occur,” the Storm Prediction Center warned in an outlook issued early Tuesday.
Strong winds are coming. This is a particularly dangerous situation — in other words, the worst-case scenario in terms of fire weather. Be aware of your surroundings. Be prepared to evacuate, especially in high fire risk areas. Be careful of sources of fire. #cawx pic.twitter.com/476t5Q3uOw
— NWS Los Angeles (@NWSLosAngeles) January 7, 2025
The prerequisites for January fires in Southern California could not be worse. After two years of ample moisture, especially in 2022-23, the state's 2024-25 rainy season is beginning to diverge sharply: unusually wet in NoCal and near-record dry in Southern California. We're now in the midst of a weak to borderline La Niña, which is typically wet to the north and dry to the south along the U.S. West Coast, but the stark contrast this winter is particularly striking. Taking the rainfall from October to December 2024 as an example, there are two typical cases:
- Eureka, California: 23.18 inches (12th Wetland 139 years of data; 1991-2020 average 15.27 inches)
- San Diego, California: 0.14 inches (third driest) 175 years of data; 1991-2020 average is 2.96 inches)
As of December 31, Southern California has not yet entered a severe to abnormal drought, according to the U.S. Drought Monitor. But as reflected in the Evaporative Demand Drought Index (a measure of how “thirsty” the atmosphere is over a given time frame) in Figure 1 below, the landscape is drying out rapidly.
In addition to unusually dry conditions for early January, we are now in the heart of the Santa Ana wind season. These notorious and dangerous downslope winds occur when strong winds blow over the coastal mountains and toward the coast, typically plaguing coastal Southern California multiple times each year. This week's peak winds may be more from the north than the northeast, and the associated wind-carrying mountain waves (formed by vertical temperature profiles at mountaintops) may be stronger than in a classic Santa Ana event. Hitting the coast further.
The National Weather Service warns that this could be the strongest Santa Ana wind event in Southern California in 13 years, since December 1, 2011, when 97 mph was recorded at Whitaker Peak (elevation 4120') in Los Angeles County ( gusts of 156 mph). High winds downed thousands of trees and knocked out power to more than 200,000 homes, mostly in the San Bernardino Valley towns of Altadena and Pasadena
There is no research to suggest that such downslope winds will become more intense or frequent with human-caused climate change, or that we should expect them to be so. But it's clear, as California weather expert and climate researcher Daniel Swain documented in a 2021 study, Southern California's fire season is lengthening and will likely continue to lengthen (see this 2022 study). These shifts will open the door for summer-dry vegetation to remain dry and highly flammable until winter rains arrive (even after New Year's Day).
While this week's weather isn't unusually warm, warmer temperatures overall are causing more water to evaporate from landscapes and reservoirs, making droughts more dangerous.
Clarity Angle: The Problem with “Hurricane Gusts”
Some media have mentioned that winds in Southern California this week may bring “hurricane-level gusts.” However, this term can be misleading. A hurricane is defined as a tropical cyclone continued Wind speed is at least 74 mph (65 knots or 119 km/h). But a given hurricane's peak gusts are typically 20 to 30 percent higher than the maximum sustained winds. Therefore, a minimal hurricane with sustained winds of 75 mph is expected to produce peak gusts of 90 to 100 mph.
The tricky part is that wind gusts of 75 mph or more are sometimes called “hurricanes.” But it doesn't take a hurricane to produce such gusts. Even tropical storms with maximum sustained winds of only 60 mph can come into play. Additionally, winds in downslope storms associated with mountainous areas are often more variable than hurricanes, sometimes going from near calm to peak intensity within minutes. So keep in mind that the Santa Ana storm, with peak gusts of 80 mph, while still scary and highly dangerous, does not produce the same winds as a Category 1 hurricane.
Jeff Masters contributed to this article.
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