The US state of California is bracing itself for Hurricane Hilary, which is already bringing fierce winds and flooding to Mexico’s Pacific coast.

It is lashing the Mexican state of Baja California with winds of up to 85 mph (140km/h). Hilary is then expected to lose speed as it moves north.

It is predicted to reach southern California as a tropical storm, the first to reach that state in 84 years.

There are warnings of “catastrophic” floods in both countries.

One man died in Baja California Sur state while attempting to cross a stream, Mexican officials said.

The Mexican government has placed 18,000 soldiers on standby to assist in rescue efforts. Nearly 26 million people in the south-western US are under flood watch.

Hilary was downgraded to a Category 1 storm after weakening on Saturday, but officials kept up their warnings.

In its first-ever tropical storm alert for California, the National Hurricane Center (NHC) said “life-threatening flooding” was likely in Baja California and the US south-west.

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,” she told a press conference on Saturday. “This is a very, very dangerous and significant storm.”

Up to 10 in (25cm) of rain is expected in parts of Mexico, California and Nevada, according to the NHC.

There is a risk of tornadoes from mid-morning through Sunday evening in parts of the Colorado River Valley, Mojave Desert and Imperial Valley.

As the storm approached, Major League Baseball rescheduled three games in southern California, while SpaceX postponed the launch of a rocket from its base on the central California coast until at least Monday.

The National Park Service also closed Joshua Tree National Park and Mojave National Preserve, both in California, to prevent visitors from being stranded in the event of flooding.

Hurricanes and tropical storms are somewhat common in Mexico. But the last time a tropical storm made landfall in southern California was in Long Beach in 1939.

Experts say the abnormal weather events plaguing the US – and several areas across the globe – are being influenced by human-caused climate change.

In the wake of the hottest month on record, July 2023, according to Nasa, the deadliest wildfire in modern US history spread across Hawaii on 8 August, killing at least 111 people.

The damage was escalated by hurricane winds passing through the area.