(PLO)- Hot, dry Santa Ana winds are believed to be the reason why wildfires in Los Angeles, California (USA) have become more intense and difficult to extinguish.
On January 7, wildfires in Los Angeles, California (USA) broke out and spread into residential areas, creating a horrifying scene.
As of January 11, the fires had burned tens of thousands of acres in the region. Tens of thousands of homes and other structures, including several schools, had been destroyed and many people had died. Authorities in California evacuated more than 180,000 residents. With strong winds, firefighters were also having difficulty controlling the flames.
According to The Conversation , these days, Santa Ana winds with hurricane-force gusts have swept through some areas of Los Angeles. This is also one of the reasons why wildfires spread.
So what are Santa Ana winds? What causes these extreme winds in Southern California, and why do they create such dangerous wildfires?
What causes Santa Ana winds?
The Santa Ana winds are strong, dry winds that blow down from the mountains toward the southern California coast. The area sees an average of about 10 Santa Ana winds per year, typically occurring from fall through January.
When the weather is dry like it is now, these winds can create a serious bushfire risk.
Santa Ana winds occur when there is high pressure in eastern California and a low pressure system offshore. Air masses move from high pressure to low pressure, and the greater the pressure difference, the faster the wind blows.
Topography also plays a role in the formation of the Santa Ana winds. As the winds blow off the tops of the San Gabriel Mountains, they become drier and hotter. As a result, by the time they hit Altadena, where the fire broke out on January 7, the relative humidity of the wind was below 5%, meaning there was essentially no moisture.
These strong, dry winds typically reach speeds of around 30 to 40 mph. However, they can be stronger. Gusts in early January 2025 were reported to have exceeded 80 mph.
Why is the risk of wildfires in California so high right now?
Southern California typically gets enough rain this time of year to keep vegetation moist and flammable. A study a few years ago found that fall moisture reduces the risk of wildfires fueled by Santa Ana winds.
However, this year, Southern California has been experiencing very dry conditions with very little moisture over the past few months, so when the Santa Ana winds come, they create extremely favorable conditions for fires to flare up.
Fighting a fire in these conditions is difficult. If there is a fire caused by Santa Ana winds, firefighters will evacuate people first and then try to control the fire. However, fighting a fire in these conditions is not easy. Therefore, firefighters need to wait for the winds to subside before they can control the fire more easily.
Other states have seen similar fires driven by strong winds. In the Chimney Tops 2 fire in Tennessee in November 2016, strong winds pushed flames into homes, killing 14 people and destroying more than 2,500 homes. Strong winds blowing down from the mountains fueled the Marshall Fire in December 2021, which destroyed about 1,000 homes in Boulder County, Colorado.
Do Santa Ana winds change over time?
Santa Ana winds are not uncommon . However, scientists have noticed they occur more frequently at this time of year.
A recent study compared 71 years of Santa Ana wind events , starting in 1948. The study found that Santa Ana winds occur less frequently in September and more frequently in December and January. Many have suggested that the increased frequency of Santa Ana winds is partly due to climate change, but so far there has been no significant evidence to support this claim.
California is seeing more devastating wildfires than ever before. That's not just due to changes in climate and winds, but also population growth.
According to The Conversation , many Californians have recently chosen to live on the edge of wildland areas, and the government has also extended the power grid to these areas. That creates more opportunities for wildfires to break out.
During severe weather, power lines are at greater risk of being struck by falling tree branches, which can spark fires. Power line fires are becoming more frequent. Today, they are the primary source of wildfires in Southern California.
The Eaton Fire, which broke out on January 7, destroyed several homes in the foothills of the San Gabriel Mountains. Few people lived here about 50 years ago. At that time, parts of the area were surrounded by citrus groves, so if a fire broke out, it would burn through the orchards before reaching homes.
Today, scientists say there is no buffer zone between homes and wilderness. The Eaton Fire’s ignition point appears to have been near or in one of the residential neighborhoods.
People's houses are also made of dry materials. Therefore, when combined with dry air, they easily catch fire, causing fires to spread quickly through residential areas and create a great risk of damage.
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