Hurricane Hilary has weakened as it heads towards Mexico's Pacific coast and California but could still cause "life-threatening" flooding, US meteorologists warn.
With winds of 85 mph (140 km/h), it has been downgraded to a Category 1 storm.
Heavy rain lashed parts of Mexico's Baja California peninsula and the south-western US overnight.
One man died after being swept away while crossing a stream in Baja California, an official said.
The man had been travelling in a car with his three children and a woman. The others all survived, local media reported.
Hilary is expected to weaken further to a tropical storm before it reaches southern California. Even still, it would be the first tropical storm to hit the US state in more than 80 years.
In its latest update at 06:00 GMT on Sunday, the US National Hurricane Center (NHC) said Hilary was roughly 90 miles (145km) south of Baja California's westernmost point of Punta Eugenia.
Its centre will "move close to the west-central coast of the Baja California peninsula" on Sunday morning and will then move across southern California on Sunday afternoon, the NHC said.
"Hilary appears to be weakening quickly," John Cangialosi, a senior hurricane specialist at the NHC, told the Associated Press news agency on Saturday.