Between autumn and spring, the Southern California experiences gusts of dry wind that cause residents to have runny noses and watery eyes. These are known as the Santa Ana winds.
The natural phenomenon usually occurs in the western United States and is very dangerous when combined with other weather conditions, such as drought, increasing the risk of causing the forest fires that are ravaging Los Angeles.
Santa Ana Winds
According to reports, the wind gusts reached hurricane force and combined with the dry wind, all caused these fires to spread rapidly.
NBC News reported on its website that "about 29,000 acres have been burned by the Palisades and Eaton fires that began on Tuesday, as well as by three smaller fires that started on Wednesday."
"The low moisture content in the vegetation we have during these periods of extreme drought creates extremely vulnerable conditions," said Mark Gold, director of water scarcity solutions at the Natural Resources Defense Council. "And when a major Santa Ana wind event hits, that's when the nightmare really begins for our firefighters."
Winds can reach 40 mph.
The Santa Ana winds are formed in the western part of the country, known as the Great Basin (Nevada and part of Utah). The basin is at a higher altitude than Southern California.
During the cold months (September to May), the cold air moves westward, towards low pressure areas along the southern coast of California. As the air passes through, it goes through mountains and canyons, "where it gains speed and becomes warmer and drier". The winds can reach speeds of up to 40 miles per hour.
Robert Fovell, professor of atmospheric and environmental sciences at the University of Albany, said: “It went over the San Gabriel Mountains and formed what is called a downslope windstorm,” he said. “That directed the strongest winds towards the hills around Eaton Canyon.”