Tropical storm Gonzalo is expected to turn into a hurricane over the Atlantic Ocean by Thursday, the US National Hurricane Centre (NHC) said on Wednesday.
A hurricane watch has been issued for nearby Barbados, it added.
Gonzalo, which is set to become the first hurricane of the season, broke the record for being the earliest seventh named storm to form over the Atlantic. The previous record was set by Tropical Storm Gert in 2005.
Gonzalo was first supposed to remain a storm, but the NHC changed its forecast, as it was moving to the west-northwest at about 12 kmh (14 mph). It is expected to reach the southern Caribbean by the end of the week.