Late on Sept. 25, 1939, a violent storm lashed Southern California, sinking boats, flooding mountain resorts and killing nearly 100 people. It was the last tropical cyclone to make landfall in the region.

Now, more than 80 years later, Hurricane Hilary is barreling toward the southwestern United States, threatening to dump enough rain to cause flash flooding and other “rare and dangerous impacts,” the National Hurricane Center said.

Such events are extremely unusual in the region because the dry air, cool water and wind conditions off California’s coast tend to break up hurricanes. Storms in the eastern north Pacific “tend to party hard, crash hard,” said Phil Klotzbach, a hurricane researcher at Colorado State University. But in the case of Hilary, slightly warmer waters caused by El Niño are helping to weaken the storm more slowly, while pressure systems are pushing the storm toward north toward land.

Along the state’s southern coast, people are preparing for an event not seen in decades.

The 1939 storm, which made landfall in Long Beach, Calif., tore through Los Angeles County and the surrounding area, destroying coastal homes, cutting power and disrupting rail and highway traffic, according to an article published in The New York Times the next day.

Nearly 100 people were killed. Some of the victims drowned at sea, while others died in flooding.

More than a dozen boats were declared missing, and the wreckage of an 80-foot yacht washed up near Huntington Beach, a usually picturesque surf spot. Around 200 people had to be rescued from wrecked leisure and fishing boats. Twenty-three people drowned when a sport fishing boat capsized just 500 feet from a pier at Point Mugu, near Oxnard. And several bodies were recovered from the water, including those of a man and a woman that washed ashore.

In Los Angeles, 5.41 inches of rain fell in 24 hours, the heaviest September rain in the city’s history at the time. A deluge in the Coachella Valley washed out train tracks and destroyed 70 percent of the region’s date crop. The overall damage was estimated to be around $2 million, the equivalent of around $44 million in today’s dollars.

The destruction was staggering. However, it could not compete with news that thousands of civilians were dying in Warsaw during the invasion of Poland. As an article in The Times noted, “Nature in her angriest moods, can scarcely hope to compete with the destruction decreed by Man.”

Other tropical storms have brought tropical storm-force winds to the Southwestern United States, but just two have made landfall in California. Besides the 1939 storm, the only other tropical storm to make landfall in the state was on Oct. 2, 1858, when a hurricane shook San Diego, damaging homes, uprooting trees and causing inland flooding. The Daily Alta California described it as “one of the most terrific and violent hurricanes ever noted,” according to a National Oceanic and Atmospheric Administration paper on the event.

Christopher Landsea, a forecaster with the National Hurricane Center and an author of the paper, noted that there were no reported injuries or fatalities.

“Back then, San Diego was just a tiny little town,” he said. “San Diego is so different now that if that same hurricane were to hit today, then the damage could be catastrophic.”