MIAMI -- Hurricane Sam was a Category 4 storm early Sunday, but forecasters said the system could fluctuate in strength over the next day or so as it churns far from land over the Atlantic Ocean.

Sam was centred about 1,455 kilometres east-southeast of the northern Leeward Islands on Sunday morning, the U.S. National Hurricane Center said. It was moving west-northwest at 13 km/h.

Forecasters said Sam had maximum sustained winds around 230 km/h. Wind speeds were expected to vary in intensity over the next day or so, followed by some slow weakening.

No coastal watches or warnings were in effect, however swells from Hurricane Sam could cause dangerous rip current conditions off the coast of the Lesser Antilles early this week, officials said.