DIAMOND BAR, Calif. − Historic Hilary − downgraded from a hurricane to a Tropical Storm but still carrying the potential for “dangerous to catastrophic” flooding − made landfall in the Mexican peninsula of Baja California on Sunday while churning north toward the U.S.

Hilary was 215 miles south-southeast of San Diego when the National Hurricane Center released its latest update at 11 a.m. Pacific Time, warning of “catastrophic and life-threatening flooding likely over Baja California and portions of the Southwestern U.S. through Monday.”

With winds of up to 65 mph and heavy rainfall, Hilary could become the first Tropical Storm to slam Southern California in 84 years. More immediately, it threatened the Mexican cities of Ensenada and Tijuana, the latter just on the border.

President Joe Biden, who is traveling to Hawaii on Monday to survey damage from devastating wildfires in Maui, urged “everyone in the path of this storm to take precautions and listen to the guidance of state and local officials.”

Jake Sojda, senior meteorologist at Accuweather, said Los Angeles and San Diego likely would be doused by multiple inches of rain. The worst of the storm was targeting the mountains and desert east of the cities, he said.

“We are talking about bona fide tropical storm conditions,” Sojda told USA TODAY. “We’re expecting 4 to 8 inches of rain as a general range across the eastern mountain slopes, and 10 to 12 inches certainly is not out of the question.”

There is an end in sight, though. Sojda said showers and clouds will linger Monday, and then Tuesday “the nice weather finally returns in force.”

Tropical Storm Hilary tracker:Follow the storm’s path as it heads toward Southern California

Forecast developments:

◾California Gov. Gavin Newsom proclaimed a state of emergency, and authorities issued an evacuation advisory for Santa Catalina Island, 23 miles off the coast.

◾As the storm rolls north, portions of Oregon and Idaho could see as much as 3 to 5 inches of rain, producing some “significant” flash flooding, the weather service said.

Hilary potentially an ‘extraordinary event’

AccuWeather meteorologists warned that Hilary could slam some of the desert areas and mountains in Southern California to southern Nevada with a life-threatening flooding disaster. In San Bernardino County, east of Los Angeles, the sheriff’s office issued evacuation orders for several towns.

Dan DePodwin, AccuWeather’s director of forecasting operations, said some areas could see more than a year’s worth of rain within a day or two.

“The impact from Hilary has the potential to be an extraordinary event, one that is rare and unprecedented,” he said.

Sandbags are hard to find

In Diamond Bar, a city of 55,000 about 20 miles east of downtown Los Angeles, locals raced to the three city fire departments Saturday in a fruitless effort to score sandbags to protect their homes from the storm. Residents had begun filling up sandbags Friday and officials said one station ran out within an hour.

On Saturday, one station in the west side of the city got two shipments of sand, but it went out as fast as it came in, according to Los Angeles County Fire captain Jesse Vasquez. Vasquez said many people who picked up sandbags from the stations were panicking, taking more than they could possibly need.

“We can’t go out there and argue with them,” he said. “We can educate and ask and plead with them. But at that point, they’re going to do whatever they want to do.”

All fire stations – operated by Los Angeles County – will be fully staffed with more equipment than normal in the city Sunday, Vasquez said. But depending on the intensity of the weather, it might be difficult to come to the aid of residents as rescue workers try to evacuate anyone severely impacted. In a city with so many hills, mudslides are a concern.

“The department is prepared,” he said. “We do our best to protect life and property. That’s our main objective.”

In Chino Hills, getting ready for a possible evacuation

In Chino Hills, 35 miles east of Los Angeles in San Bernardino County, resident Veronica Kemble beat the rush. She shopped early Saturday for food and other essentials for herself, her husband and their cats, as well as items she might need if they are forced to evacuate. Kemble said she tried to avoid major stores such as Costco and found items she needed at discount store locations. She expressed concern for people doubting the severity of the storm, saying their was no need to panic, but that people should be “prepared just in case” the worst happens.

“I figured if it rains really hard and the stores are closed, or if they start to lose power, you’re not going to be able to buy this stuff,” Kemble said.

Homeless vulnerable as Hilary advances

Volunteers have been driving the streets of Los Angeles passing out tarps and plastic bags to people without homes so they can try and keep themselves and their belongings dry. The Los Angeles Sheriff’s Department warned those without a place to stay to move away from riverbeds and other likely flooding locations.

In Venice Beach, west of downtown Los Angeles, Bobby Geivet arrived at about 6:30 a.m. with a cooler, weathered guitar, a tarp and a plan. Geivet, 45, said he’s homeless but not defenseless against the storm. He tied his tarp between two palm trees and anchored it by using a stone to pound makeshift stakes into the ground. He said he planned to set up a hammock underneath the tarp. 

“I like to be high and dry,’’ he said. “It’s going to be wet, but I want to be as dry as I can.’’ 

Joshua Tree National Park closed because of flooding concerns

Coachella Valley could see year’s worth of rain over a few days

Palm Springs braces for flooding

Farther inland in Riverside County, weather service meteorologist Elizabeth Adams said rain could fall up to 3 inches an hour Sunday near Palm Springs, across the desert and mountains surrounding the Coachella Valley. The intense rainfall during those hours could cause widespread and life-threatening flash floods, Adams said.

The National Weather Service placed the Coachella Valley under a tropical storm warning, emphasizing the potential for high winds and extreme flooding rain that “may prompt numerous evacuations and rescues.” Palm Springs Fire Chief Paul Alvarado urged residents not to ignore barricades and other warnings on local roads.

“Local responders use them to safely direct traffic out of flooded areas,” Alvarado said. “We want to avoid swift water rescues, which put the lives of both drivers and public safety at risk.”

Historic ‘heat dome’ poised to sweep nation

Meteorologist Ryan Maue said a “historic, climate-induced heat dome will absolutely demolish records” in coming days, peaking Thursday when 67 million Americans are forecast to experience at least 100 degree temperatures.

“Heat domes don’t get names or categories yet,” Maue said on social media. “But this one would be Category 5.”

Tropical Storm Emily takes shape but may not last long

What began as a large area of low pressure off the Cabo Verde Islands has become well-defined enough to earn a name and designation.

Tropical Storm Emily, with maximum sustained winds of almost 50 mph, was heading west-northwest in the Atlantic Ocean at nearly 10 mph Sunday.  However, Emily is expected to weaken and lose its status as a tropical storm in the coming days.

Contributing: Claire Thornton, USA TODAY; Kate Franco, Palm Springs Desert Sun; The Associated Press