The storm packed 40 mph (65 kmh) winds as it headed west at 13 mph early on Sunday morning. It was forecasted to be near central Lesser Antilles late on Monday or early Tuesday, the National Hurricane Center (NHC) said.
The National Hurricane Center sees the possibility of Dorian moving into a harsher environment by Wednesday night and Thursday.
"Monday night into Tuesday night, islands stretching from St. Vincent northward to Guadeloupe should prepare for wind gusts of 50-60 mph, sporadic power outages and localized flooding due to 2-4 inches of rainfall,” AccuWeather Senior Meteorologist Dan Pydynowski said.
The NHC said it was likely to issue additional watches for portions of the Windward and Leeward Islands Sunday, noting that Puerto Rico and Hispaniola should monitor Dorian's progress.
“It should be stressed that Dorian is likely to be a difficult cyclone to forecast due to the marginal environment it is embedded within and its small size,” the Hurricane Center wrote.
Many Caribbean islands are likely to receive 2 to 4 inches (5 to 10 cm) of rain, but some part of the Lesser Antilles islands could get 6 inches, the NHC said.
The NHC said they are also watching “98L,” an area several hundred miles offshore Florida-Georgia border. They said that there is an 80 percent chance that the weather system will intensify and will graduate into a tropical storm or even a hurricane by mid-week. It will be named Erin if it turns into a storm.