Hurricane Maria becomes 'extremely dangerous' stormWatch
It is due to hit the Leeward Islands, which include the US and British Virgin islands, in the coming hours.
Maria is moving roughly along the same path as Irma, the hurricane that devastated the region this month.
Martinique declared a maximum-level alert while another French island, Guadeloupe, ordered evacuations.
Hurricane warnings were also issued for Puerto Rico, Dominica, St Kitts and Nevis, Montserrat, St Lucia and the US and British Virgin Islands.
A hurricane watch is in place for St Martin, Saba, St Eustatius and Anguilla.
Some of these islands are still recovering after being hit by Hurricane Irma - a category five hurricane which left at least 37 people dead and caused billions of dollars' worth of damage.
US President Donald Trump declared a state of emergency for the US Virgin Islands on Monday.
The Leeward Islands, where Maria will first strike, include Antigua and Barbuda. The latter island was evacuated after being devastated by Hurricane Irma.
The US National Hurricane Center (NHC) has warned that heavy rainfall caused by the hurricane "could cause life-threatening flash floods and mudslides".
Quite unthinkable really that on the back of Hurricanes Harvey and Irma, we're now seeing another major hurricane, this one seemingly on course to strike those affected by Irma a couple weeks back. You really have to feel for those in the Caribbean right now
Its truly saddening. All the people in the Caribbean have been through a lot in these past couple of weeks.