Hurricane Melissa has continued its devastating sweep across the Caribbean, decimating homes and infrastructure, flooding neighbourhoods and leaving dozens dead.

The impact in Jamaica was clearer on Wednesday, after the island nation was hit squarely by the category five storm - one of the most powerful hurricanes ever measured in the region. At least five people have been confirmed dead there.

At least another 20 died during flooding in Haiti as Melissa, now a category two storm, tore through the region.

In Jamaica, people remain stranded on roofs and without power. Prime Minister Andrew Holness noted the total devastation across the island-nation.

He added that 80-90% of roofs were destroyed, along with hospitals, libraries, police stations, port houses, and other urban infrastructure.

King Charles, who is the head of state in Jamaica, said in a statement that he is deeply concerned and profoundly saddened at the damage caused by Melissa in Jamaica and across the Caribbean.

This most dreadful of record-breaking storms reminds us of the increasingly urgent need to restore the balance and harmony of Nature for the sake of all those whose lives and livelihoods may have been shattered by this heartbreaking disaster, he said.

From Jamaica, where the storm also caused mudslides, Melissa moved north to Cuba as a category three storm, bringing 115 mph winds and heavy rain, battering the southeast of the island.

Cuba President Miguel Díaz-Canel asked residents to not let their guard down and said that the country prepared for a worst-case scenario, which helped its response.

A tropical storm warning is in place for the Turks and Caicos Islands and the slow-moving hurricane is expected to increase in speed in the coming days.

The US is sending a disaster response team to Jamaica to assess the scale of need in the hurricane's aftermath and formal requests for help have come from Haiti and The Bahamas. Melissa is not expected to make landfall in North America.