Elsa strengthened into the first hurricane of the Atlantic season on Friday as it battered the eastern Caribbean, where officials closed schools, businesses and airports under the threat of flash flooding and landslides.

Heavy rains and winds lashed Barbados as the Category 1 storm headed for islands including St. Vincent and the Grenadines, which are still struggling to recover from recent volcanic eruptions.

Elsa was located about 95 miles (155 kilometers) east of St. Vincent and was moving west-northwest at 28 mph (44 kph). It had maximum sustained winds of 75 mph (120 kph), according to the National Hurricane Center in Miami.

A hurricane warning was in effect for Barbados, St. Lucia and St. Vincent and the Grenadines.

Authorities opened dozens of shelters in St. Vincent and urged people to evacuate if they lived near a valley, given the threat of flash flooding, mudslides and lahars, especially in the northern part of the island where La Soufrière volcano is located.

“They will move anything within its path,” said St. Vincent Prime Minister Ralph Gonsalves. “Do not wait until it's too late to go to a shelter.”

He said 94 shelters are open, adding that it's a smaller number than in previous years because some 2,000 people remain in other shelters following massive volcanic eruptions that began in early April.

A tropical storm warning was in effect for the southern coast of Dominican Republic from Cabo Engano to the border with Haiti and the entire coast of Haiti. A tropical storm watch was in effect for Grenada, Saba, Sint Eustatius and Jamaica, while a hurricane watch was in effect for Haiti's southern region from the capital, Port-au-Prince, to the southern border with the Dominican Republic.

Elsa is the earliest fifth-named storm on record, beating out last year’s Eduardo which formed on July 6, according to Colorado State University hurricane researcher Phil Klotzbach.

Elsa was expected to move into the eastern Caribbean Sea late Friday and Friday night, and pass near the southern coast of Hispaniola, which is shared by Haiti and the Dominican Republic, on Saturday. The storm was then expected to move near Jamaica and portions of eastern Cuba on Sunday.

The storm was forecast to produce rainfall totals of 3 to 6 inches (7 to 15 centimeters) with maximum totals of 10 inches (25 centimeters) inches on Friday across the Windward and southern Leeward Islands, including Barbados. The rain could unleash isolated flash flooding and mudslides.