Tropical Storm Hilary brought flooding rains to southern California and Nevada as forecasters warned of life-threatening and catastrophic conditions from the rare storm as it moved inland.
The U.S. National Weather Service urged people to stay off roads in the Los Angeles area due to dangerous flooding.
Many of the areas in the path of the storm, which was expected to weaken to a tropical depression as its center moved into Nevada later Monday, are not used to seeing the type of rainfall associated with a tropical storm.
Forecasters said some desert areas could end up with 12 to 25 centimeters of rain.
"In some places in the desert, that’s a year’s worth," Alex Tardy, a senior meteorologist for the National Oceanic and Atmospheric Administration in San Diego, told a news briefing. "The normal rainfall in Southern California and San Diego is nothing in August. So, a very unusual event is unfolding here."
California Governor Gavin Newsom declared a state of emergency to help with response and recovery efforts.
U.S. President Joe Biden said his administration stood ready to provide assistance to California, Nevada and Arizona.
The storm forced the cancellation of flights in Los Angeles, San Diego and Las Vegas, while schools in Los Angeles and San Diego were closed Monday.
The last tropical storm to strike California came in 1977.
Tropical Storm Hilary made landfall Sunday in Mexico’s Baja California peninsula.
Some information for this story came from The Associated Press, Agence France-Presse and Reuters