A hurricane warning has been extended to cover the whole of Jamaica, Haiti and parts of the Bahamas.
The Turks and Caicos islands have also been placed on hurricane alert.
Hurricane Matthew has killed at least three people, caused cruise ships to change itineraries and prompted the governors of Florida and North Carolina to declare states of emergency for coastal areas.
“Life-threatening flash floods and mudslides are likely from this rainfall in southern and northwestern Haiti, the southwestern Dominican Republic and eastern Cuba,” the US National Hurricane Centre warned.
As much as 40 inches of rain is forecast together with hazardous seas and winds of up to 140mph as the category four storm heads north across the region.
Hurricane Matthew is expected to reach eastern Cuba late this afternoon local time before heading towards the Bahamas.
British travellers to the Caribbean regional affected by the hurricane are being advised by the Foreign and Commonwealth Office to monitor its progress and follow the advice of local authorities.