Puerto Rico activated the National Guard and canceled the start of classes in public schools as forecasters warned that the U.S. territory would be hit by Tropical Storm Ernesto, which formed in the Atlantic Ocean on Monday.

Tropical storm warnings were in effect for Puerto Rico, Vieques, Culebra, the U.S. and British Virgin Islands, Antigua, Barbuda, Anguilla, St. Kitts, Nevis, Montserrat, Guadeloupe, St. Martin, St. Barts and St. Maarten.

Officials in the French Caribbean said the storm was expected to drench Guadeloupe on Monday and pass near St. Barts and St. Martin. The National Hurricane Center said Ernesto is forecast to move over or near Puerto Rico and the U.S. and British Virgin Islands on Tuesday evening.