Tropical Storm Darby bore down on Hawaii, prompting its governor to declare an emergency over a storm expected to make landfall with strong winds and heavy rain.
Forecasters said Darby would reach the US state's Big Island on Saturday when maximum sustained winds could near 80 kilometres per hour and as much as 40 cm of rain could fall, the National Weather Service said in an advisory.
The torrential rainfall could cause life-threatening flash floods as well as landslides, it said.
"I urge residents and businesses to follow emergency instructions, prepare for the storm and take steps to protect your families, employees and property," Hawaii Governor David Ige said in an emergency proclamation statement.
The storm was about 160km southeast of Hilo early on Saturday, the National Weather Service said.
It issued a tropical storm warning for Hawaii County on the Big Island, as well as for the islands of Maui, Molokai, Lanai and Kahoolawe.
Surf swells generated by Darby are likely to hit the Hawaiian Islands over the next couple of days.