Beryl strengthened into a hurricane Saturday as it churned toward the southeastern Caribbean, with forecasters warning it was expected to become a dangerous major storm before reaching Barbados late Sunday or early Monday.

A major hurricane is considered Category 3 or higher, with winds of at least 111 mph (178 kph). On Saturday night, Beryl was a Category 1 hurricane, marking the farthest east that a hurricane formed in the tropical Atlantic in June, breaking a record set in 1933, according to Philip Klotzbach, Colorado State University hurricane researcher.

A hurricane warning was issued for Barbados, St. Lucia, Grenada, and St. Vincent and the Grenadines. A tropical storm warning was posted for Martinique and Tobago and a tropical storm watch for Dominica.

“It’s astonishing to see a forecast for a major (Category 3+) hurricane in June anywhere in the Atlantic, let alone this far east in the deep tropics. #Beryl organizing in a hurry over the warmest waters ever recorded for late June,” Florida–based hurricane expert Michael Lowry posted on X.

Beryl’s center was forecast to pass about 26 miles south of Barbados, said Sabu Best, director of the island’s meteorological service. Forecasters then expect the storm to cross the Caribbean on a path toward Jamaica and eventually Mexico.

On Saturday night, Beryl was centered about 660 miles east–southeast of Barbados, with maximum sustained winds of 80 mph. It was moving west at 22 mph.

“Rapid strengthening is now forecast,” the Miami–based U.S. National Hurricane Center said.

Atmospheric science researcher Tomer Burg noted that Beryl was just a tropical depression with 35 mph winds Friday.

“This means that according to preliminary data, Beryl already met rapid intensification criteria before even becoming a hurricane,” he wrote on the social media platform X.

Warm waters were fueling Beryl, with ocean heat content in the deep Atlantic the highest on record for this time of year, according to Brian McNoldy, University of Miami tropical meteorology researcher.

Beryl also is the strongest June tropical storm on record that far east in the tropical Atlantic, according to Klotzbach.

“We remain absolutely vigilant and need to take every precaution that is possible for ourselves, for our family and for our neighbors,” Barbadian Prime Minister Mia Mottley said in a public address Saturday night, asking that all businesses close by Sunday evening. “We do not want to put anybody’s life at risk.”