Tropical storm warnings have been issued for Puerto Rico, the US and British Virgin Islands and other nearby islands as tropical storm Bertha approaches the Caribbean.
The storm's maximum sustained winds early are near 45mph with no significant change in strength expected over the next two days.
In addition to Puerto Rico and the Virgin Islands, tropical storm warnings are in effect for Babados, St Lucia, Dominica, Vieques and Culebra. A tropical storm watch is in effect for St Vincent and the Grenadines.
Bertha is centred about 170 miles east of Barbados and is moving west-northwest near 20mph.
The US National Hurricane Centre says Bertha is expected to pass near or north of Barbados on Friday.