More than 41 million Americans across California, southern Nevada and northwest Arizona are under flood watches on Wednesday amid a rare, high risk for excessive rainfall and flooding. This includes major metros like Los Angeles, San Francisco, Sacramento, California, San Diego and Las Vegas.

A California storm on Christmas Eve caused flooding and mudslides, and prompted evacuations, power outages, and travel warnings as heavy rains hit the region.

Residents of Los Angeles spent the day before Christmas under rain showers and winds of around 40 mph, while the New England area braces for heavy snow later in the week.

The National Weather Service extended a Flash Flood Warning for parts of Southern California as the region gets hit with several inches of rainfall and strong winds.

Officials in Los Angeles and surrounding counties warned that a "very dangerous" holiday storm could trigger "widespread flash flooding."

Heavy rain and flash flooding have soaked roads in northern California, leading to water rescues and at least one confirmed death.