MIAMI – Tropical Storm Otto on Tuesday strengthened to a Category 1 hurricane with maximum sustained winds of 75 mph (120 km/h) as it continued to move toward Costa Rica and Nicaragua, the U.S. National Hurricane Center said.
As of 21:00 GMT, the storm was located 305 miles (485 km) east-southeast of Bluefields, Nicaragua, and roughly 235 miles (375 km) east of Puerto Limon, Costa Rica.
Otto, the seventh hurricane of the Atlantic season, was moving west at 2 mph (4 km/h), the NHC said.
The NHC forecasts that Otto will approach the coasts of Costa Rica and Nicaragua on Thursday.
The storm is expected to experience some additional strengthening before making landfall.
Otto became a hurricane with just eight days left in the season.
A hurricane watch is in effect from the Costa Rica-Panama border to south of Bluefields. The Colombian island of San Andres and the area of Panama from Colon to Nargana island are under a tropical storm warning.
A hurricane warning may be issued for coastal areas in Nicaragua and Costa Rica by early Wednesday, the NHC said.