Thousands flee highland fire in California as Santa Ana winds fan the flames

(CNN) — A wildfire in Riverside County, California, spread due to hot, dry Santa Ana winds, charring several buildings and forcing thousands of people from their homes.

When he called fire highlands, It was first reported Monday at 12:37 PM PT (3:27 PM Miami time), near Aguanga, California, and covers an area of ​​just 5 hectares. Seven hours later, the fire had burned more than 485 hectares, according to the California Department of Forestry and Fire Protection. Cal Fire.

By early Tuesday morning, the highland fire had burned 890 hectares and was 0% contained, the agency reported. The fire destroyed at least three buildings and damaged six others.

Evacuation orders were first issued Monday afternoon, but were quickly expanded hours later and again Tuesday morning.

More than 1,100 homes in the fire area have been evacuated, affecting about 4,000 people, Riverside Fire spokeswoman Maggie Klein De La Rosa told CNN. A further 1,700 people have been warned they may also have to evacuate.

Evacuation orders and warnings, the latter intended to notify residents to prepare for an evacuation order, remain in effect.

According to the National Weather Service, sustained winds of 32 km/h to 40 km/h with gusts up to 56 km/h are expected in the Highland Fire and surrounding areas this Tuesday. These winds will continue to pose a challenge to firefighters and could continue to fan the fire.

At least 310 firefighters from 49 fire companies were working to respond to the blaze Tuesday, according to Cal Fire.

The cause of the fire is still under investigation.

Although its origin is still unclear, it is no mystery how the highland fire was able to grow so quickly. Extremely dry air and strong winds in California on Monday and Tuesday contributed to the rapid spread of the fire.

Relative humidity, a measure of the amount of moisture in the air, was very low on Monday: between 5% and 15%, according to a forecast from the National Weather Service in San Diego. When relative humidity drops, fires start and can be easily maintained.

Once they form, wind gusts cause these fires to spread quickly, and even cause their embers to fly away to start other fires. Wind speeds exceeded 80 kilometers per hour near the fire, driven by the Santa Ana phenomenon that began over the weekend in parts of Southern California.

The Santa Ana wind, named after the mountain range in Southern California, is a warm, dry monsoon wind created when air flows from east to west, which typically occurs during the fall and winter.

When air moves from mountain highlands to sea level, it is compressed by the higher pressure, warming and drying the air. Santa Ana winds can be very strong as they rush down the mountain, enhanced by canyons and passes that act as natural wind tunnels. Winds can dry out plants, making them more vulnerable to fires, and fanning the flames of existing fires.

So far in 2023, California’s wildfires have been well below average, with more than 130,000 hectares burned as of October 31. Typically, fires have burned about 600,000 hectares of California by this time of year, according to Cal Fire.

CNN’s Sheri Mossburg contributed to this report.