Hurricane Hilary was downgraded to a tropical storm before making landfall along Mexico's Baja coast on Sunday, amid warnings it could bring deadly flash floods.

The US National Weather Service warned it was still likely to bring "catastrophic and life-threatening" flooding to  northwestern Mexico as well as southern California, where it will be the first such tropical storm in 84 years

As of 1500 UTC, the storm still sustained wind speeds of up to 70 miles per hour (110 kilometers per hour).

"Heavy rains" were also affecting portions of Baja California and the southwestern United States.

Wild weather begins in Mexico

As Hilary pummeled Mexico's Baja California peninsula with rain, one person drowned in the town of Santa Rosalia when their vehicle was swept away by an overflowing stream.

Rescue workers managed to save four other people around the nearby township of Mulege.

Authorities in Mexico's second largest city, Tijuana, have moved some residents to temporary shelters as the threat of landslides looms.

"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," said Rafael Carrillo, head of the Tijuana fire department.

Meanwhile, Mexico's navy evacuated 850 people from islands off the Baja coast and deployed 3,000 troops around the region.

Preparations underway in the US

In the US, California Governor Gavin Newsom declared a state of emergency on Saturday and officials urged people to finish final preparations for the storm, saying that leaving it until Sunday would be too late.

Nancy Ward, director of the California Governor's Office of Emergency Services, said Hilary could be one of the worst storms to hit the state in more than a decade.

"Make no mistake, this is a very, very dangerous and significant storm," she said.

The US Federal Emergency Management Agency (FEMA) said it deployed teams to areas in Hilary's path and is providing President Joe Biden with regular updates.

"He has encouraged everyone to make sure that they are aware of what this dangerous storm is potentially going to bring and to listen to their local officials on the steps they can take to make sure that they are keeping safe," FEMA chief Deanne Criswell said.

Almost 200 flights on Sunday and another 184 on Monday were canceled at the San Diego International Airport, per FlightAware website.

kb,zc/wd (AP, AFP, Reuters)