Tropical storm Ida formed in the southwestern Caribbean on Wednesday, quickly gaining muscle and threatening to become a hurricane before making landfall in Nicaragua.

Nicaraguan authorities readied shelters, saying evacuations were likely in the coastal city of Bluefields and the towns of Laguna de Perlas, Cruz de Rio Grando and Kukra Hills.

"We're taking precautions for the storm, which we expect will hit our territory on Thursday," said Lt. Col. Reinaldo Carrion, the head of Civil Defense in Bluefields. "We are ready to act."

Maximum sustained winds were at 65 mph, according to the U.S. National Hurricane Center in Miami. The center said further strengthening was expected and the storm could become a hurricane before making landfall early Thursday.

The ninth tropical storm of the season was centered about 60 miles east of Bluefields and moving northwest near 7 mph.

A hurricane watch was in effect for the eastern coast of Nicaragua from Bluefields to the border with Honduras.

Storm warnings remained in effect for the entire eastern coast of Nicaragua but were discontinued for the Colombian islands of San Andres and Providencia.