Tropical Storm Beta, the record 23rd storm of the Atlantic hurricane season, has strengthened since developing in the southwestern Caribbean late Wednesday.

The U.S. National Hurricane Center says Beta is expected to dump up to 25 centimeters of rain across western Panama, Costa Rica, northeastern Honduras, Nicaragua, and the Colombian islands of San Andres and Providencia.

At last report the storm was located 115 kilometers south-southeast of San Andres Island and about 260 kilometers east of Bluefields, Nicaragua. Forecasters say Beta is expected to continue slowly drifting north, bringing its center near San Andres on Friday.

Colombia has issued a hurricane warning for San Andres and Providencia. A hurricane watch is in effect for Nicaragua's entire Caribbean coast.

Tropical Storm Beta is not expected to threaten the United States.