Hurricane Hilary roared toward Mexicos Baja California peninsula late Saturday as a downgraded but still dangerous Category 2 hurricane that’s likely to bring catastrophic flooding to the region and cross into the southwest U.S. as a tropical storm.

While it’s still expected to enter the history books as the first tropical storm to hit Southern California in 84 years, Hilary weakened from a Major Category 3 hurricane down to a Category 2 storm at midday Saturday and is expected to lose strength further as it treks northward.

Hilary appears to be weakening quickly, John Cangialosi, a senior hurricane specialist at the National Hurricane Center, wrote in a Saturday update posted online. The eye is filling and the cloud tops in the eyewall and rainbands have been warming during the past several hours.

Forecasters said the storm could bring heavy rainfall to the southwestern United States, dumping 3 to 6 inches (8 to 15 centimeters) in places, with isolated amounts of up to 10 inches (25 centimeters), in portions of southern California and southern Nevada. Meteorologists also expect the storm to churn up life-threatening surf conditions and rip currents including towering waves up to 40 feet (12 meters) high along Mexicos Pacific coast.

Officials issued an evacuation advisory for the tourist destination of Santa Catalina Island, 23 miles (37 kilometers) off the Southern California coast, while authorities in Los Angeles scrambled to get the homeless off the streets and into shelters.

And the Miami-based hurricane center issued tropical storm and potential flood warnings for Southern California from the Pacific coast to interior mountains and deserts. The San Bernardino County sheriff on Saturday issued evacuation warnings for several mountain and foothill communities ahead of the storm.

Courtney Carpenter, a National Weather Service warning coordination meteorologist, said experts forecast flash floods, mudslides, isolated tornadoes and wind damage to Southern California.

Heavy rainfall and strong winds alreading were setting in Saturday, and power outages are expected.

Hilary on Friday had rapidly grown into an exceedingly dangerous Category 4 Major hurricane for a time with top sustained winds of 145 mph (230 kph) at its peak. Its maximum sustained winds initially dropped to 115 mph (185 kph) on Saturday as a Category 3 storm, before further weakening to 110 mph (177 kph) making it a Category 2.

It was still 640 miles (1030 km) south-southeast of San Diego, California. It was moving north-northwest at 17 mph (28 kph) and was expected to turn more toward the north and pick up speed.

Forecasts said the storm was swirling off one of the westernmost spurs on Mexicos southern Baja peninsula. The hurricane was expected to brush past Punta Eugenia on that coast before making landfall along a sparsely populated area of the peninsula about 200 miles (330 kilometers) south of the Pacific port city of Ensenada.

Hilary is then expected to rake northward up the peninsula, threatening heavy rains and dangerous flooding in the border city of Tijuana, where many homes in the city of 1.9 million cling precariously to steep hillsides. The city ordered all beaches closed Saturday, and set up a half-dozen storm shelters at sports complexes and government offices.

Rafael Carrillo, the head of the Tijuana fire department, voiced the fear that was at the back of everyones mind in Tijuana, particularly residents of the poorly built hillside homes.

If you hear noises, or the ground cracking, it is important for you to check it and get out as fast as possible, because the ground can weaken and your home could collapse, Carrillo said.

The U.S. National Park Service closed California’s Joshua Tree National Park and Mojave National Preserve to keep visitors from becoming stranded amid flooding. Cities across the region, including in Nevada and Arizona, offered sandbags to safeguard properties against floodwaters. Major League Baseball rescheduled three Sunday games in Southern California, moving them to Saturday as part of split doubleheaders,

SpaceX delayed the launch of a satellite-carrying rocket from a base on Californias central coast until at least Monday. The company said conditions in the Pacific could make it difficult for a ship to recover the rocket booster.

President Joe Biden said Friday the Federal Emergency Management Agency had pre-positioned staff and supplies in the region. I urge everyone, everyone in the path of this storm, to take precautions and listen to the guidance of state and local officials, he said.

Officials in Southern California were re-enforcing sand berms, built to protect low-lying coastal communities against winter surf, like in Huntington Beach, which dubs itself as Surf City USA.

In nearby Newport Beach, Tanner Atkinson waited in a line of vehicles for free sandbags at a city distribution point.

I mean a lot of people here are excited because the waves are gonna get pretty heavy, Atkinson said. But I mean, its gonna be some rain, so usually theres some flooding and the landslides and things like that.

Mexicos Navy evacuated 850 people from islands off the Baja coast, and deployed almost 3,000 troops for emergency operations.

About 100 people sought refuge at storm shelters in the twin resorts of Los Cabos, at the southern tip of the Baja peninsula, and firefighters used an inflatable boat to rescue a family in San Jose del Cabo after the resort was hit by driving rain and wind.

In La Paz, the picturesque capital of Baja California Sur state on the Sea of Cortez, police patrolled closed beaches to keep swimmers out of the whipped-up surf.