The National Hurricane Center said Monday that Hurricane Eta had rapidly strengthened into a major category 3 storm and that further strengthening was possible before landfall Tuesday.
Eta could slam into the northeastern coast of Nicaragua with category 4 force winds of 140 miles per hour.
"Catastrophic wind damage is expected where Eta's eyewall moves onshore, and preparations should be rushed to completion within the Hurricane Warning area," wrote a NHC forecaster.
Storm surge impacts of 12 to 18 feet above normal tide levels are also possible.
After landfall, Eta or its remnants will weaken, but drift slowly over Central America dumping heavy rains. The NHC warns of life-threatening flash flooding, river flooding and landslides.
Forecasters are also watching to see if Eta or its remnants re-emerge over the Caribbean, while noting confidence in the long-range forecast is very low at this time.