Early in the hurricane season, an unusually strong storm moves through the Caribbean

Beryl strengthened from a tropical storm into a hurricane on Saturday as the storm makes its way through the southeast Caribbean.

A hurricane warning is now in effect for Barbados, while Saint Lucia, Saint Vincent and the Grenadines and Grenada are under a hurricane watch. A tropical storm watch was issued for Martinique, Dominica and Tobago. Forecasters are warning that the hurricane is expected to turn into a major hurricane on Sunday.

“The reality is that we need to be ready,” Barbados Prime Minister Mia Amor Mottley said in a statement on Friday. She urged residents to stock up on medication and to have vital identification documents that might be needed in case there's a reason to evacuate.

A major hurricane is a Category 3 hurricane or higher, with winds of at least 111 miles per hour. On Sunday morning, Beryl's maximum sustained winds had reached 100 mph. It was located 565 miles east-southeast of Barbados and moving west at 21 mph.

Three to six inches of rain are expected in Barbados and the Windward Islands, with a storm surge of five to seven feet forecast. Localized flooding is expected in the area as well.

Beryl is only the second named storm in what is to be a busy hurricane season this year. Last week, Tropical Storm Alberto led to torrential flooding for portions of southern Texas and northeastern Mexico, and was responsible for four deaths in the region, according to The Associated Press.

A named storm this far east is unusual for June, John Cangialosi, a forecaster with the National Hurricane Center, wrote in an advisory Friday.

“There have only been a few storms in history that have formed over the central or eastern tropical Atlantic this early in the year,” he wrote.

The Atlantic hurricane season is supposed to see the most activity in mid-August, even though hurricane season begins on June 1. However, in a report released last month, the National Oceanic and Atmospheric Administration (NOAA) predicted that this year's hurricane season would be “above average,” with 17 to 25 storms, eight to 13 hurricanes and four to seven major hurricanes of Category 3 or higher.

“Past is not necessarily prologue when it comes to the hurricanes of the future,” NOAA Administrator Rick Spinrad said to reporters when the report was released in May. “The key this year, as is any year, is to get prepared and stay prepared.”

Beryl has been intensified by warmer ocean temperatures in the deep Atlantic. NOAA reports that ocean heat content is the highest on record for this time of year. Usually, the El Niño atmospheric oscillation would help suppress hurricane activity, but that pattern is diminishing, which will most likely create a suitable atmosphere for storms like Beryl to form.

Barbados hosted the T20 cricket World Cup final between India and South Africa on Saturday. Weather was clear at the Kensington Oval stadium and the game began on time, but Prime Minister Mottley is still conscious of tourists who may not be aware of the danger lurking on Sunday.

“We have a duty to ensure that all who are here are also in a position to prepare themselves for any eventuality,” Mottley said.