Erin became a Category 3 hurricane in the Caribbean early Saturday and is expected to strengthen further during the day, the National Hurricane Center reported.

The storm is currently 170 miles (275 kilometers) northeast of Anguilla with maximum sustained winds of 120 mph (195 kph). It is moving west-northwest at 20 mph (31 kph).

It is currently not forecast to hit land, but strong winds are affecting nearby islands, prompting forecasters to warn of possible flooding and landslides.. The NHC said it currently expected Erin to become a Category 4 storm later Saturday but to eventually swerve away from the continental United States.

Tropical storm watches are in place for St. Martin and St. Barthelemy and Sint Maarten. Up to 4 inches (10 centimeters) are expected, with isolated totals of up to 6 inches (15 centimeters), according to the National Hurricane Center in Miami.

“Locally, considerable flash and urban flooding, along with landslides or mudslides, are possible,” the NHC said.

Hurricane specialist and storm surge expert Michael Lowry said Erin is forecast to eventually take a sharp turn northeast that would put it on a path between the U.S. and Bermuda.

“All of our best consensus aids show Erin turning safely east of the United States next week, but it’ll be a much closer call for Bermuda, which could land on the stronger eastern side of Erin,” he said.

Erin is the fifth named storm of the Atlantic hurricane season, which runs from June 1 to Nov. 30, but the first to reach hurricane status.

“Erin is forecast to explode into a powerful Category 4 hurricane as it moves across very warm waters in the open Atlantic. Water temperatures at the surface and hundreds of feet deep are several degrees higher than the historical average,” said Alex DaSilva, Accuweather’s lead hurricane expert.

This year’s season is once again expected to be unusually busy. The forecast calls for six to 10 hurricanes, with three to five reaching major status with winds of more than 110 mph (177 kph).

The U.S. government has deployed more than 200 employees from the Federal Emergency Management Agency and other agencies to Puerto Rico as a precaution as forecasters issued a flood watch for the entire U.S. territory from late Friday into Monday.

Puerto Rico Housing Secretary Ciary Pérez Peña said 367 shelters have been inspected and could be opened if needed.

The U.S. Coast Guard said Friday that it closed six seaports in Puerto Rico and two in the U.S. Virgin Islands to all incoming vessels unless they had received prior authorization.

Meanwhile, officials in the Bahamas said they prepared some public shelters as a precaution as they urged people to track the hurricane.

“These storms are very volatile and can make sudden shifts in movement,” said Aarone Sargent, managing director for the Bahamas’ disaster risk management authority.