Santa Ana winds facts for kids
The Santa Ana winds, sometimes called the devil winds, are strong, very dry winds. They blow from inland areas towards the coast in Southern California and northern Baja California. These winds start from cool, dry areas of high pressure air in the Great Basin.
Santa Ana winds are known for bringing hot, dry weather. This often happens in autumn, which can be the hottest time of the year. They can also occur at other times. These winds usually bring the lowest humidity levels of the year to coastal Southern California. They also create "beautifully clear skies."
The low humidity, warm air, and strong winds create dangerous conditions for wildfires. These conditions can cause fires to start and spread quickly.
About 10 to 25 Santa Ana wind events happen each year. A wind event can last from one to seven days. The average event lasts about three days. The longest one recorded was 14 days in November 1957. Strong winds often cause damage in certain areas. These include the Santa Ana River basin in Orange County and the Santa Clara River basin in Ventura and Los Angeles County. Damage also occurs near Newhall Pass and Cajon Pass.
The Santa Ana Winds cause most wildfires in Southern California. For example, they were a major force behind the January 2025 Southern California wildfires.
Contents
How Santa Ana Winds Form
Understanding the Wind's Journey
The Santa Anas are a type of wind called katabatic winds. This means they flow downhill from higher places towards sea level. The National Weather Service describes them as "strong, hot, dust-bearing winds." They blow from inland desert regions to the Pacific Coast near Los Angeles.
Santa Ana winds begin with high-pressure air over the Great Basin and upper Mojave Desert. If there is a low-pressure area over the Pacific Ocean, it can pull this high-pressure air. This creates a "pressure gradient," like a slope for the air to flow down. The air then moves south along the eastern side of the Sierra Nevada mountains. It then enters the Southern California region.
A simple way to predict a Santa Ana event is to check the air pressure. If the pressure difference between Los Angeles International Airport and Las Vegas is about 9 millibars, Santa Ana winds are likely. Dry air spirals clockwise out from the high-pressure center. This dry air crosses the deserts of eastern California. It then hits the tall Transverse Ranges mountains. These mountains separate coastal Southern California from the deserts.
The air takes the easiest path through mountain passes. It flows from the high pressure in the Great Basin to the low pressure off the coast. This movement channels the air through passes like Soledad Pass, Cajon Pass, and San Gorgonio Pass. These passes are known for making the Santa Ana winds even stronger.
Why the Winds Get Strong and Dry
The winds speed up as they squeeze through narrow passes. This is like the Venturi effect, where air moves faster through a smaller opening. As the air moves from high elevations to lower ones, it warms up. This warming happens naturally as air is compressed. It warms about 5 degrees Fahrenheit for every 1,000 feet it drops.
As the air warms, its relative humidity drops. The air is already very dry from its journey over the deserts. This extra warming often makes the humidity fall below 10 percent. The result is a strong, warm, and very dry wind. These winds blow out of mountain passes into valleys and coastal areas. They can easily go over 40 miles per hour. These warm, dry winds can make brush or forest fires much worse, especially during dry conditions.
During Santa Ana conditions, it is often hotter along the coast than in the deserts. Coastal Southern California can see its highest temperatures of the year in autumn, not summer. Very cold, dry air from Canada can create the strongest Santa Ana winds.
Santa Ana winds are different from Föhn winds. Föhn winds get warm from rain on one side of a mountain. This rain releases heat, making the air warmer on the other side. An example is the Chinook wind.
If Santa Ana winds are strong, the usual daytime sea breeze might not happen. Or it might be very weak. This is because the strong winds blowing from land to sea fight against the sea breeze. At night, Santa Ana winds combine with the land breeze. They become even stronger. This happens because the inland desert cools more than the ocean at night.
People often think of Santa Ana winds as hot and dry. But cold Santa Anas also exist. These cold winds are often linked to the strongest wind speeds across the region.
How Santa Ana Winds Affect the Region
Wildfire Danger
Santa Ana winds often bring the lowest relative humidity of the year to coastal Southern California. This low humidity, combined with warm, compressed air and high wind speeds, creates dangerous fire conditions. The mix of wind, heat, and dryness turns the chaparral plants into explosive fuel. This feeds the famous wildfires that Southern California is known for.
Benefits of the Winds
Even though the winds can be destructive, they also have some benefits. They cause cold water to rise from deep in the ocean. This process is called "upwelling." This cold water brings many nutrients that help local fish. When the winds blow over the ocean, the water temperature drops about 4 degrees Celsius (7 degrees Fahrenheit). This shows that upwelling is happening. The amount of chlorophyll (a sign of tiny ocean plants) in the surface water increases greatly when the winds are present.
Impact on Ocean and Boats
During Santa Ana winds, large ocean waves can form. These waves come from the northeast. They hit the sides of the Channel Islands that are usually calm. This includes popular islands like Catalina and Santa Cruz. Harbors and anchorages that are normally safe, like Avalon and Two Harbors, can have high surf and strong winds. These winds can even pull boats from their moorings. Boaters are advised to move their boats to the southern side of affected islands or return to the mainland during Santa Ana conditions.
Other Wind Phenomena
Santa Ana Fog
A Santa Ana fog can happen after a Santa Ana wind event ends. When Santa Ana winds are blowing, the air over the coast is very dry. This dry air also extends out over the Pacific Ocean. When the Santa Ana winds stop, cool and moist air from the ocean can quickly form a "marine layer." This marine layer becomes very moist, creating low clouds or fog. If the wind then shifts to blow from the ocean towards land, this sea fog can move onto coastal areas.
This causes a sudden change from hot, dry Santa Ana conditions to cool, moist, and gray marine weather. The Santa Ana fog can cover cities in as little as fifteen minutes. However, a true Santa Ana fog is rare. It needs specific conditions for the marine layer to form quickly and for winds to shift strongly. More often, the high-pressure system that caused the Santa Ana winds weakens slowly. In this case, the winds stop, but warm, dry conditions can continue for days or weeks.
A similar thing happens when Santa Ana conditions are weak. Hot, dry air can build up in inland valleys but not reach the coast. People driving from the San Fernando Valley, where it's sunny and warm, might cross the Santa Monica Mountains. They then enter cool, cloudy air and fog from the marine layer. Both this and the "Santa Ana fog" are examples of an air inversion. This is when a layer of warm air sits above a layer of cooler air.
Sundowner Winds
Similar winds happen in the Santa Barbara and Goleta areas. These are called sundowner winds. They occur most often in late spring to early summer. They are strongest around sunset, which is why they are called "sundowner." High-pressure areas usually move east. This often causes "sundowner" wind events to happen a day or two before Santa Ana events.
History of the Winds
The Santa Ana winds and the wildfires they cause have been a part of the Los Angeles Basin for over 5,000 years. This dates back to the first people living in the area, like the Tongva and Tataviam. People have written about Santa Ana winds in English records since at least the mid-1800s. During the Mexican–American War in 1847, Commodore Robert F. Stockton reported a "strange, dust-laden windstorm."
Throughout history, these hot, dry winds have been described as dust storms, hurricane-force winds, and strong north-easters. They have damaged homes and destroyed fruit orchards. Old newspaper photos show damage from these winds. When the Los Angeles Basin was mostly farms, farmers especially feared the winds because they could ruin crops.
The strongest Santa Ana winds ever recorded happened in early December 2011. In Pasadena and Altadena, winds blew steadily at 97 miles per hour. Gusts reached up to 167 miles per hour. Mammoth Mountain had a near-record wind gust of 175 miles per hour on December 1, 2011.
Wildfires and the Winds
Because they are both gusty and drying, Santa Ana winds are strongly linked to wildfire danger. These winds have caused some of the biggest and deadliest wildfires in the area and the state.
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Major fires fueled by Santa Ana winds before 2000 include the Santiago Canyon Fire (1889), Bel Air Fire (1969), and Laguna Fire (1970, 1993).
From 2000 to 2019, big Santa Ana-fueled fires included the Cedar Fire (2003), Old Fire (2003), Esperanza Fire (2006), and Witch Creek Fire (2007). Other major fires were the Thomas Fire (2018) and the December 2017 Southern California wildfires.
From 2020 to today, major fires include the El Dorado Fire (2020) and Bobcat Fire (2020). The Santa Ana winds made a series of wildfires in January 2025 much worse. These fires, like the Eaton Fire and Palisades Fire, burned over 35,000 acres and killed 24 people. The winds during these fires reached over 80 miles per hour in some places. This is as strong as a Category 1 hurricane.
Health Effects of the Winds
The winds can carry tiny spores of fungi called Coccidioides immitis and Coccidioides posadasii. These fungi cause a disease called Coccidioidomycosis, also known as "Valley Fever." About 40 percent of people who get infected show symptoms. These symptoms are usually like the flu, with fever, cough, headaches, rash, and muscle pain.
More serious problems can include severe pneumonia and lung problems. The fungus can also spread throughout the body. This "disseminated" form of Valley Fever can cause skin ulcers, bone damage, severe joint pain, and heart problems. It can also lead to meningitis (brain infection) and can sometimes be deadly.
Where the Name Comes From
The name Santa Ana winds comes from the Santa Ana Canyon in Orange County. This is one of many places where the winds blow very strongly. The Santa Ana Canyon, Santa Ana River, and the town of Santa Ana were all named after Saint Anne. This is because the Portolá expedition entered the river valley on Saint Anne's feast day in 1769.
Newspaper articles mentioned the name Santa Ana winds as early as the 1870s and 1880s. According to research, the first mention was in 1871 in the Anaheim Gazette. For people in what would become Orange County, the winds seemed to come from Santa Ana Canyon.
The name Santa Ana wind became widely known after a big news story in 1901 about wind damage. However, local business leaders thought linking the winds to the town would be bad for business. They claimed that calling them Santa Ana winds was "incorrect and libelous." So, they started a campaign saying the name was actually "an Indian word."
They claimed the term Santa Ana wind came from a Native American phrase for "big wind" or "devil wind." They said this was then changed by Californios to "Satanás" (meaning Satan), and later to "Santa Ana." However, experts on local Native American languages say this supposed term never existed. There is no proof to support this story, and it is a false etymology. Another false idea is that the name refers to General Santa Anna of Mexico. This idea suggests the name came from dust clouds kicked up by his cavalry horses.
The Santa Ana Journal newspaper fought for years to separate the winds from the town's name. In 1935, it published a poem about the "devil winds": "The devil sends the naughty winds / To blow the skirts on high; / But God is just and sends the dust / To fill the bad man's eye."
In 1933, Father John O'Connell of Mission San Juan Capistrano reported that an old resident, Don Jesus Aguilar, said that in his day, the winds were called el viento del norte ("the north wind").
Images for kids
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A hygrometer showing low humidity during a Santa Ana wind event.
See also
In Spanish: Vientos de Santa Ana para niños
- Geography of southern California
- Climate of Los Angeles
- Climate of San Diego
- Climate change in California
- El Niño–Southern Oscillation
- Australian foehn winds
- Berg wind
- Bora (wind)
- Chinook wind
- Diablo wind
- Khamsin
- Norte (wind)
- Nor'west arch
- Oroshi
- Sirocco
- Washoe Zephyr
