MANAGUA, Nicaragua — A fast-strengthening Hurricane Iota became a very dangerous Category 5 storm as it swept over the western Caribbean early Monday, approaching the same part of Central America battered by a similarly powerful Hurricane Eta just over a week ago.

Forecasters said Iota’s maximum sustained winds had reached 155 mph, and were growing stronger, potentially making for a catastrophic Category 5 hurricane by the time it reaches the coast.

Authorities warned that Iota would probably come ashore over areas where Eta’s torrential rains saturated the soil, leaving it prone to new landslides and floods, and that the storm surge could reach a shocking 12 to 18 feet above normal tides.

Evacuations were being conducted from low-lying areas in Nicaragua and Honduras near their shared border, which appeared to be Iota's likely landfall. Winds and rain were already being felt on the Nicaraguan coast Sunday night.

Iota became a hurricane early Sunday and rapidly gained more power. It was expected to pass over or near Colombia's Providencia island during the night, and the U.S. National Hurricane Center warned it would probably reach the Central America mainland late Monday.

The hurricane center said Iota was centered about 20 miles off Isla de Providencia, Colombia, and 145 miles southeast of Cabo Gracias a Dios on the Nicaragua-Honduras border, and moving westward at 10 mph.

Iota is the record 30th named storm of this year’s extraordinarily busy Atlantic hurricane season. Such activity has focused attention on climate change, which scientists say is causing wetter, stronger and more destructive storms.

All of Honduras was on high alert, with compulsory evacuations that began before the weekend. By Sunday evening 63,500 people were reported to be in 379 shelters just in the northern coastal region.

Nicaraguan officials said that by late Sunday afternoon about 1,500 people, nearly half of them children, had been evacuated from low-lying areas in the country's northeast, including all the inhabitants of Cayo Misquitos. Authorities said 83,000 people in that region were in danger.

Wind and rain were beginning to be felt Sunday night in Bilwi, a coastal Nicaraguan city where people crowded markets and hardware stores during the day in search of plastic sheeting, nails and other materials to reinforce their homes, just as they did when Hurricane Eta hit on Nov. 3.

Several residents of Bilwi expressed concern that their homes would not stand up to Iota, so soon after Eta. Local television showed people being evacuated in wooden boats, carrying young children as well as dogs and chickens.

Eta already wreaked havoc. It hit Nicaragua as a Category 4 hurricane, killing at least 120 people as torrential rains caused flash floods and mudslides in parts of Central America and Mexico. Then it meandered across Cuba, the Florida Keys and around the Gulf of Mexico before slogging ashore again near Cedar Key, Florida, and dashing across Florida and the Carolinas.

Iota was forecast to drop 8 to 16 inches of rain in northern Nicaragua, Honduras, Guatemala and southern Belize, with as much as 30 inches in isolated spots. Costa Rica and Panama could also experience heavy rain and possible flooding, the hurricane center said.

Eta was this year's 28th named storm, tying the 2005 record. Remnants of Theta, the 29th, dissipated Sunday in the eastern Atlantic Ocean.

The official end of hurricane season is Nov. 30.