Jose strengthened into a Category 3 hurricane on the Saffir-Simpson wind scale and is expected to become a major hurricane on Friday, the U.S. National Hurricane Center (NHC) said in its latest advisory on Thursday. The hurricane is now headed to the Caribbean, posing a grave threat to the islands.

Jose was about 660 miles (1,060 km) east of the Lesser Antilles with maximum sustained winds of 105 miles per hour (165 km/h), the NHC said.

Additional strengthening is forecast during the next 48 hours, the NHC added.