People leave a hotel where they sheltered during Hurricane Matthew in Les Cayes, Haiti, on Thursday. [Photo/Agencies]

Hurricane Matthew edged ever closer to Florida on Friday with torrential rains and up to 190 kilometer-per-hour winds after a blast through the Caribbean that left more than 300 people dead in Haiti.

Matthew was downgraded to a Category Three storm early in the day by the National Hurricane Center, as its wind speed dropped slightly. But Florida still faced its most dangerous hurricane in living memory.

It was not clear if it would be a direct hit or more of a sideswiping blow, which could still be catastrophic.

Only a handful of hurricanes of this strength have ever made landfall in Florida, and none since 1898 has threatened to scythe its way north along the low-lying, densely populated coast into Georgia and beyond.

Evacuation orders were issued for areas covering about 3 million residents.

Daytona Beach imposed a curfew that was to last until dawn on Saturday, and President Barack Obama declared emergencies in Florida, Georgia and South Carolina, promising federal aid.

Matthew has already battered Haiti, Jamaica, Cuba, the Dominican Republic and the Bahamas, and US officials were taking no chances, warning that loss of life was a virtual certainty.

The Red Cross has launched an emergency appeal to provide immediate relief to 50,000 Haitians in the aftermath of the hurricane.

The International Federation of the Red Cross and Red Crescent Societies is seeking $6.92 million to help provide medical relief, shelter, water and sanitation over the next year to people affected by Hurricane Matthew in southwestern Haiti.