Tropical Storm Ernesto headed towards Honduras and Mexico's Yucatan peninsula early Tuesday, with US forecasters predicting it would reach hurricane strength before making landfall.
The Miami-based National Hurricane Center (NHC) said Ernesto was packing winds of 65 miles (105 kilometers) per hour as it powered across the Caribbean toward the west-northwest at a speed of 20 kilometers an hour.
At 0600 GMT, the eye of the storm was located about 520 kilometers east of Belize City, and was expected to approach the Yucatan coast late Tuesday or early Wednesday.
"Some strengthening is expected, and Ernesto is forecast to become a hurricane before it reaches the Yucatan peninsula," the center said.
Forecasters said the storm could dump heavy rain along the coasts of Nicaragua and Honduras, as well as on the Yucatan peninsula -- home to several resort towns -- and parts of Belize.
"These rains are likely to cause dangerous flash floods and mudslides over higher terrain," the US hurricane center said, also warning of the risk of a storm surge in coastal areas.
A hurricane warning was in effect for the entire coast of Belize, and parts of the Yucatan Peninsula's east coast.
In Mexico, authorities in Quintana Roo state evacuated two fishing villages and ordered the closure of the port of Chetumal, the state capital. The state is home to Cancun and the island of Cozumel, a popular cruise ship stop.
Some 1,500 people have been evacuated from Nicaragua's coastal areas and from the Miskito Cays island chain, with authorities predicting strong winds and powerful waves.
In Honduras, where rains were already lashing the coast, authorities issued a "24-hour yellow alert" into Tuesday, readied evacuation plans and prepared to deliver humanitarian aid.
And in Guatemala, equipment and other humanitarian support have been sent to northern regions of the country in preparation for the storm's effects.