SAN JUAN, Puerto Rico (AP) — Heavy rains pelted the northern Caribbean on Tuesday as forecasters warned that a disturbance could soon become Tropical Storm Fred following a quiet month of no named storms in the region.

The National Hurricane Center issued tropical storm warnings for the U.S. Virgin Islands and Puerto Rico, where forecasters expected the potential cyclone to strengthen Tuesday into the sixth named storm of the Atlantic hurricane season.

“The most important thing today is preparation,” said Puerto Rico Gov. Pedro Pierluisi. “I am not going to minimize the potential impact of this event…we expect a lot of rain.”

He said government agencies would close by noon on Tuesday.

The Dominican Republic, Haiti and the southern Bahamas could get hit on Wednesday, and people in Florida were urged to monitor updates. Still, forecasters said it remained uncertain where the storm could move by later in the week.

Heavy rains hit parts of the eastern Caribbean overnight, including the islands of Guadeloupe and Dominica.

More than a month has passed since the last Atlantic storm, Hurricane Elsa, but this time of summer is usually the season’s busiest.

The hurricane center issued warnings for Puerto Rico, the U.S. Virgin Islands and the Dominican Republic on the south coast from Punta Palenque eastward and on the north coast from Cabo Frances Viejo eastward. In addition, a watch was in effect for Saba, St. Eustatius, and Hispaniola’s north coast, from Cabo Frances in the Dominican Republic to Gonaives, Haiti.

The Turks and Caicos Islands and the southeastern Bahamas were also under a tropical storm watch, including the Acklins, Crooked Island, Long Cay, the Inaguas, Mayaguana, and the Ragged Islands.

The disturbance labeled Potential Tropical Cyclone Six had maximum sustained winds of 35 mph (55 kph) with higher gusts and was 220 miles (350 kilometers) east-southeast of Ponce, Puerto Rico, according to officials. A tropical storm has maximum sustained winds of at least 39 mph (63 kph).

The storm was expected to produce rainfall of 2 to 4 inches (5 to 10 centimeters) over the Leeward Islands, Virgin Islands, and Puerto Rico, with up to 6 inches (15 centimeters) in some areas, leading to flooding and mudslides.