Heavy rain and wind from a tropical storm have downed trees, knocked out power and prompted evacuations of several homes on Hawaii’s Maui island but spared the state widespread damage before moving out to sea.

Tropical Storm Olivia crossed the state on Wednesday, making landfall on Maui and Lanai islands along the way.

Weather forecasters warned heavy rains would continue through Thursday but Maui mayor Alan Arakawa said he was hopeful the effects of the storm would be limited.

Floodwater in a car park in Lahaina
Floodwater in a car park in Lahaina (Lauren Greer/AP)

“It’s been an ordeal but we’re coming through this fairly well,” he said at a news conference.

“I’m not seeing any really large areas of damage, no homes destroyed or flooded to any kind of extreme measures as we did in previous storms.”

The Central Pacific Hurricane Centre said Olivia was south west of Honolulu late on Wednesday. It was moving west with maximum sustained winds of 40mph, barely strong enough to qualify as a tropical storm.

The hurricane centre said Olivia will probably weaken further and become a tropical depression by Thursday.

Maui County said several homes in Lahaina had to be evacuated because of rising water in a nearby river. Another home in Waihee Valley was evacuated.

A flash flood warning was issued for Molokai island and Maui. A wind gust of 51mph was recorded at the airport on the island of Lanai.

A gauge recorded 9in of rain at West Wailua Iki on Maui.

The storm, which was a hurricane earlier in the week, slowly lost power as it neared the state.

Forecasters cancelled a tropical storm warning for Oahu and Maui late on Wednesday after the storm moved far enough south to put the islands out of range for stronger winds.

Matthew Foster, a meteorologist with the hurricane centre, said moisture from Olivia will linger through to Friday even though the wind threat has died.

This, combined with an upper level system, may trigger heavy rain and possibly thunderstorms on Kauai, Oahu and Molokai, he said.

Honolulu’s H1 freeway flooded under similar circumstances two years ago after Tropical Storm Darby passed the state and dissipated, he noted.

Hawaii governor David Ige and Honolulu mayor Kirk Caldwell said they were keeping an eye on the leftover moisture.

“We’re all being cautious. We all do need to be very cautious until tomorrow,” Mr Caldwell said.

President Donald Trump has signed a disaster declaration for Hawaii, which will help the Federal Emergency Management Agency respond, the governor said.