It appeared headed eventually in the general direction of the US state of Florida.

The category one storm is the first hurricane to hit Barbados in more than 60 years, unleashing heavy rains and winds on the island and then on St Vincent and the Grenadines, which are struggling to recover from recent massive volcanic eruptions.

Elsa was centred about 800 kilometres southeast of Santo Domingo and was moving west-northwest at 48km/h, with maximum sustained winds of 140km/h, according to the US National Hurricane Center in Miami.

"That level of sustained wind can blow down a lot of buildings and cause a lot of damage," St Vincent Prime Minister Ralph Gonsalves said.

"I am pleading with you. Let us not take this hurricane lightly. This is not the time to play the fool."

The long-term forecast track showed it heading toward Florida as a tropical storm by Tuesday morning.

Authorities in Barbados said they received calls about families trapped in their homes, collapsed houses and power and water outages, but no reports of serious injuries or deaths.

A hurricane warning was in effect for Jamaica and from the Haitian capital of Port-au-Prince to Punta Palenque in the Dominican Republic.

Elsa is the earliest fifth-named storm on record, beating out last year's Eduardo which formed on July 6, Colorado State University hurricane researcher Phil Klotzbach said.

He said it was also the farthest east that a hurricane has formed this early in the tropical Atlantic since 1933.

Australian Associated Press