Nadine, with maximum sustained winds of 45 mph, was about 475 miles south-southwest of the Azores and moving west-southwest at 5 mph, the National Hurricane Center said in its 5 9.m. EDT advisory.
No watches or warnings were in effect.
Nadine was expected to turn toward the south-southwest Tuesday night and then turn toward the south Wednesday.
Tropical storm-force winds extended 195 miles from the storm center. Some strengthening is possible during the next two days.