▶ Watch Video: Southern California braces for storm after Hilary makes landfall in Mexico

Southern California and the Southwest were preparing for “catastrophic and life-threating flooding” as Tropical Storm Hilary continued north after making landfall in the northern part of Mexico’s Baja California peninsula on Sunday. 

Hilary had strengthened to a Category 4 hurricane before weakening to a tropical storm prior to making landfall. The storm is still expected to bring heavy rainfall along its path from Sunday afternoon into Monday morning, according to the latest advisory from the National Hurricane Center

“The potentially historic amount of rainfall is expected to cause life-threatening to catastrophic flash, urban, and arroyo flooding including landslides, mudslides, and debris flows through early Monday morning,” NHC said. 

Tropical storm conditions, including gusty winds, were expected to begin on Sunday afternoon in parts of the Southwestern U.S., according to NHC. Large swells generated by Hilary, which can cause life-threatening surf and rip current conditions will affect portions of Southern California over the next two days, the center warned.

Where is flooding expected? 

Rainfall amounts of 3 to 6 inches, with isolated amounts of 10 inches, are expected across portions of Southern California and southern Nevada, according to the NHC.

In Nevada, officials remain concerned about dangerous flooding across the western Mojave Desert, which is at high risk for flash flooding, “an exceedingly rare occurrence,” NWS Las Vegas said Sunday on social media.

There were also flood advisories for parts of southern Nye and southern Inyo County and in the northwestern part of California’s San Bernardino County, which borders Nevada, on Sunday afternoon. 

“Do not attempt to cross flooded roadways! Turn around, don’t drown,” the National Weather Service said. 

Southern California is experiencing heavy rain in Los Angeles and surrounding counties, with heavy downpours expected between 3 p.m. today and 3 a.m. Monday morning, CBS News Los Angeles reported

In California, evacuation orders have been issued for San Bernardino and Riverside Counties. Evacuation warnings were issued in Orange County, according to CBS News Los Angeles

Meanwhile, the Inland Empire and mountains are at a high risk of flash flooding, with some communities expected to get 6-10 inches of rain, according to CBS Los Angeles.  

How is Southern California preparing for Hilary?

As of 5 p.m. ET, Hilary had maximum sustained winds of 60 mph. Although no longer a hurricane, the system was still expected to bring heavy rainfall to the area.

It is the first time that the National Hurricane Center issued a tropical storm warning for Southern California, and California Gov. Gavin Newsom declared a state of emergency ahead of the storm. 

Evacuees from Catalina Island arrive in Long Beach, California, after leaving due to Hurricane Hilary. Aug. 19, 2023. 

Genaro Molina / Los Angeles Times via Getty Images

Los Angeles County officials said Sunday they were expecting 1 to 3 inches of rain and wind speeds of 20 to 30 mph. 

“We are ready,” Los Angeles Mayor Karen Bass told “Face the Nation.” 

The tropical storm warning, which was upgraded Friday night from what was also the first-ever tropical storm watch for the region, was in effect for most of Southern California, including large swaths of San Diego, Orange, and Los Angeles Counties, along with California’s Catalina Island, according to the National Weather Service. 

L.A. County officials on Saturday were advising all Catalina residents and visitors to leave the island as soon as possible ahead of the storm’s arrival. 

The California Department of Parks and Recreation on Saturday ordered a temporary closure of all San Diego and Orange County state beaches and several state parks.  

Disneyland announced Saturday that parks would be closing early Sunday, with Disney California Adventure Park closing at 9 p.m., Disneyland Park closing at 10 p.m. and the Downtown Disney District will close at 11 p.m. 

The San Diego Padres, Los Angeles Dodgers and Los Angeles Angels all moved their scheduled Sunday home games to Saturday double-headers in anticipation of the storm.  

When will Hilary hit Las Vegas?

Hilary’s winds will continue to weaken as it approaches the U.S., but the storm is expected to bring strong rains to parts of Nevada. 

Nevada will see heavy rain into Monday morning with likely flooding in Las Vegas, and “significant flooding” in Death Valley, the Weather Channel reported

Nevada Gov. Joe Lombardo declared a state of emergency Sunday afternoon due to the “imminent impact” of Tropical Storm Hilary across the state. 

“Significant damage to public and private property are likely, including multiple transportation routes,” the declaration read. 

This comes days after he announced that 100 National Guard troops had been activated ahead of the tropical storm.