Tropical Storm Irma strengthened to a Category 2 hurricane as it moved over the Atlantic Ocean on Thursday and is expected to be “extremely dangerous” for the next several days, the National Hurricane Center said.

With sustained winds already near 100 mph, Irma is forecast to become a “major hurricane” by Thursday evening as it moves west toward the Leeward Islands. By Tuesday, the storm is expected to become a Category 4 hurricane.

It’s still too early to tell what kind of impact Irma will have on the US, but it could hit the Carolinas by Sept. 10.

“The American models take it to the Carolinas by next Sunday. The European models have it going to Cuba and possibly threatening South Florida,” WKMG Orlando meteorologist Troy Bridges said. “It’s just too early to tell.”