Hurricane Hillary triggers flood warning in northwest Mexico, California

Mexico has braced for a powerful Pacific hurricane that triggered a warning of "potentially catastrophic" flooding in a northwestern tourist region and the neighbouring US state of California.

Hurricane Hilary threatened to bring strong winds, flash floods and "life-threatening" surf and rip current conditions, the US National Hurricane Center (NHC) said on Friday.

"We are a little scared and trying to stay positive," Katrina Morgan, a tourist from the United States, said in the Mexican resort of Cabo San Lucas on the Baja California peninsula.

Hilary's maximum sustained winds reached about 230 kilometres an hour before slowing slightly, according to the NHC.

It was a Category Four hurricane – the second-most powerful on the Saffir-Simpson scale of one to five.

"Life-threatening and potentially catastrophic flooding" was likely over much of Baja California and southern California this weekend and early next week, the NHC warned.

Residents and workers in Cabo San Lucas put up protective boarding, laid sandbags and stored furniture in preparation, as large waves crashed ashore.

"We've already had to live through similar experiences. We know what can happen to us. We must be prepared with food, canned goods and candles," Marlen Hernandez, a 30-year-old restaurant worker, told AFP news agency.

Navy personnel were seen patrolling the beach in Cabo San Lucas – a popular destination for both Mexican and foreign tourists.

Hilary was located about 523 kilometres southwest of Cabo San Lucas on the southern tip of Baja California, the NHC said.

"On the forecast track, the centre of Hilary will move close to the west coast of the Baja California peninsula over the weekend and reach southern California by Sunday night," it forecast.

Rare California alert

A hurricane warning was issued for a stretch of coastline in Baja, California from Punta Abreojos to Cabo San Quintin, and a hurricane watch north from there to Ensenada.

Across the border, an unusual tropical storm watch was in effect from the California/Mexico border to Point Mugu in Ventura County, as well as for Catalina Island, according to the NHC.

"Fluctuations in intensity are likely through tonight," it predicted.

"Weakening is expected to begin by Saturday, but Hilary will still be a hurricane when it approaches the west coast of the Baja California peninsula Saturday night and Sunday. Hilary is expected to weaken to a tropical storm by late Sunday before it reaches southern California," the NHC added.

The storm brought rain and rough seas to areas along Mexico's southwestern Pacific coast, including the tourist resort of Acapulco.

President Joe Biden said 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," Biden told reporters Friday at Camp David, where he met the leaders of Japan and South Korea.

In the United States, "rainfall amounts of three to six inches, with isolated amounts of 10 inches, are expected across portions of southern California and southern Nevada. Dangerous to locally catastrophic flooding will be possible," the NHC said.

Hurricanes hit Mexico every year on both its Pacific and Atlantic coasts, usually between May and November.

Although their remnants sometimes affect California, it is rare for cyclones to hit the US state with tropical storm intensity.