Hurricane Erin exploded in strength to a Category 5 storm in the Caribbean on Saturday, rapidly powering up from a tropical storm in a single day, the National Hurricane Center said.

It quickly powered up from a tropical storm to a Category 5 in a single day, the National Hurricane Center said.

Hurricane Erin is now a Category 5 storm as it rapidly intensified and threatens the Leeward Islands and Puerto Rico, then will move along the U.S. East Coast

It continues to push toward the northern Leeward Islands, where tropical storm watches are now in effect as of the 8 p.m. update from the National Hurricane Center. Intensification is expected as Erin moves toward warmer ocean temperatures over the next several days.

Tropical Storm Erin -- which is forecast to strengthen into the first hurricane of the Atlantic season by Saturday morning -- won't have a direct impact on the U.S., but it will bring dangerous rip currents to the East Coast.