Storm Hilary flooded streets, downed power lines and triggered mudslides across Southern California on Monday after unleashing record-breaking downpours overnight, but no U.S. deaths were attributed to the storm and fears of disaster dissipated.

Hilary arrived in California as a rare tropical storm that dumped 4 to 5 inches (10 to 12 cm) of rain on coastal areas and 10 inches (25 cm) or more in the mountains, National Weather Service meteorologist Richard Thompson said. He called it the first landfallen tropical storm in Southern California since September 25, 1939.

In terrain more accustomed to drought, flash floods rushed through desert plains and mountain canyons, washing out roads.

Rain clouds gave way to clearer skies on Monday as the storm moved north. Once hurricane strength off the coast of Mexico's Baja California peninsula, it was downgraded to a post-tropical cyclone as it moved over the North American mainland.

No fatalities or significant injuries were reported in the U.S. One man was killed in Mexico when his family was swept away while crossing a stream on Saturday, Mexican officials said.

Remnants of Hilary were expected to dump heavy rains in Nevada and Utah and into the Northwest, where more than 4 million people remained under the threat of flooding until Monday night, the service said.

"Fortunately, Californians listened to their local officials and took the necessary preparedness actions to help protect themselves and their families," FEMA administrator Deanne Criswell told reporters aboard Air Force One.

The storm produced flash floods in the San Gabriel Mountains east of Los Angeles and inundated more densely populated coastal areas of Ventura County northwest of the city. Inland desert towns around the resort of Palm Springs also got walloped.

In the middle of the storm on Sunday, a magnitude 5.1 earthquake hit north of Los Angeles, generating the social media meme #hurriquake.