Irma has strengthened and become a Category 3 hurricane over the eastern Atlantic, according to the National Weather Service.
Irma's maximum sustained winds have increased to 115 mph, with higher gusts.
It is located about 720 miles west of the Cabo Verde Islands and 1,780 miles east of the Leeward Islands, and it is moving west-northwest at 12 mph.
"Fluctuations in strength, both up and down, are possible," the National Weather Service said, "but Irma is expected to remain a powerful hurricane for several days."
Irma, now a Category 2 hurricane, "is forecast to become a major hurricane by tonight and is expected to be an extremely dangerous hurricane for the next several days," according to the National Weather Service.
Irma's maximum sustained winds had increased to nearly 100 mph as of 11 a.m. EST, with higher gusts. The NWS said the hurricane is "rapidly intensifying over the eastern Atlantic."
Hurricane Irma is located about 650 miles west of the Cabo Verde Islands.
It is moving west-northwest at about 10 mph and is expected to continue moving in that direction through Friday, then head "generally westward" on Saturday.
It is forecast to become a Category 4 hurricane east of the Leeward Islands next week, the NWS said.
The Leeward Islands are located where the northeastern Caribbean Sea meets the western Atlantic Ocean. The group starts east of Puerto Rico and reaches southward.
There are no coastal watches or warnings in effect at this time.
Tropical Storm Irma on Thursday is likely morphing into the fourth hurricane of the season, according to The Weather Channel.
The Weather Channel reported that Irma is steadily intensifying in the eastern Atlantic Ocean, with its center located roughly 590 miles west of the Cabo Verde Islands.
Irma is reportedly moving westward at about 10 to 15 mph, meaning it could eventually become an immediate threat to land areas despite not currently menacing any.
The National Hurricane Center on Thursday said Irma is predicted to strengthen into a hurricane that day.
Irma will continue shifting generally westward over the next five days, riding the south side of a ridge of high pressure known as the Bermuda High.
The Bermuda High is centered in the central Atlantic, and Irma should move through a section of the ocean mostly favorable for strengthening in the next several days.
Irma may encounter dry air to its north and west, however, which may weaken the chances of it becoming a hurricane.
The storm will not hit the longitude of the eastern Caribbean Sea until the middle of next week, when it should reach the Lesser Antilles Islands.
The Weather Channel reported that it is much too early to determine if Irma will endanger either the Lesser Antilles or other areas beyond them, including the U.S.
This is additionally the first time the name Irma has been used for a hurricane or tropical storm in the Atlantic.
Irma replaced the name Irene in 2011 after the latter moniker was retired due the damage it caused the U.S. and the Bahamas during that hurricane season.
Louisiana and Texas are currently struggling with challenges stemming from what is now Tropical Depression Harvey.
Harvey struck the Texas coast last Friday as a Category 4 hurricane and has since resulted in at least 31 deaths in the U.S.