Maui is hunkered down for heavy rain and powerful wind as a gradually weakening tropical storm barrels towards Hawaii, while Honolulu hopes it will be spared the worst.

Forecasters said Tropical Storm Olivia could dump 5in to 10in of rain, with some places getting as much as 15in.

Maui mayor Alan Arakawa urged residents to store drinking water and warned they should plan for power outages, landslides, high surf, fallen trees and flooded roads.

“Nature has a real funny way of not giving us advance notice,” Mr Arakawa said.

Olivia was about 100 miles east of Maui and packing winds of 50mph late on Tuesday. The storm, which was a hurricane earlier in the week, has been slowly losing power as it nears the state.

Schools, courts and government offices will be closed in Maui County on Wednesday in preparation for the storm.

Scott Zaffram, a senior response official with the Federal Emergency Management Agency, said emergency teams and supplies were ready on Maui.

The National Guard has mobilised personnel and trucks to the east side of Maui, said Herman Andaya, administrator of the county’s emergency management agency.

Hawaiian Airlines cancelled flights by its commuter airline, Ohana by Hawaiian.

Officials were worried about landslides in west Maui because brushfires during Hurricane Lane three weeks ago wiped out vegetation, Maui County spokesman Rod Antone said.

The storm is expected to affect Hana first, and residents are bracing for the small town, with a population of 1,200, to take the brunt of the storm.

Hana is a popular day-trip destination for travellers staying in Maui’s resort towns, but officials people who don’t need to be in town to stay away because they could become trapped and take up limited shelter space.