Hurricane Earl is showing no signs of slowing down. As it made its way across the Atlantic on Monday, it rose to a Category 4 storm with winds topping 135 m.p.h., according to the National Hurricane Center. Earl grew into a Category 3 as early as Monday morning, so its rise has been rapid. Hurricane warnings were in effect for St. Martin/St. Maarten, St. Barthelemy, Saba, St. Eustatius, the U.S. and British Virgin Islands, and the Puerto Rican islands of Vieques and Culebra, and a hurricane and tropical storm watch is in effect for most of Puerto Rico. The storm “will be accompanied by large and dangerous battering waves,” and could raise water levels between one and five feet, according to the hurricane center. It’s possible that Earl will make landfall in the U.S. over Labor Day weekend, affecting areas from the Carolinas to Cape Cod, said CNN meteorologist Jacqui Jeras.