The US national hurricane centre says that Hurricane Dean was about 435km from Mexico at 10pm Irish time.
The centre is still reporting that the hurricane is likely to be upgraded to Category 5 before it makes landfall again.
It is expected to hit the coast around the border between Belize and Mexico.
Storm surges could see flooding of 4-6m above normal tide level where the hurricane makes landfall.
The area can expect at least 12-25cm of rain, but some places could get as much as 45-50cm which could trigger life-threatening flash floods or mudslides.
Tropical storm warnings remain in place for some parts of Cuba.
All warnings for the Cayman Islands are now finished.
Jamaican authorities declared a month-long state of emergency as Hurricane Dean continued its journey through the Caribbean.
Trees were uprooted and roofs ripped off houses after winds and rains battered southern Jamaica last night.
Mudslides and floods were also reported in several parts of the country.
Nine people have so far been killed in the hurricane, which is at Category Four strength, with winds of up to 145km/h.
Jamaican Prime Minister Portia Simpson Miller called a cabinet meeting to discuss the hurricane's potential impact on general elections scheduled for later this month.
The latest computer tracking models forecast that the hurricane will spare the US Gulf Coast but slam into the Yucatan, cross the Bay of Campeche and then hit central Mexico.
The US space shuttle Endeavour is heading back to Earth from the International Space Station so it can land a day early in case the storm forces NASA to evacuate its Houston center.
Hurricane warnings are in effect for the coast of Belize and the east coast of the Yucatan Peninsula, all the way to the popular tourist destination of Cancun.
The Department of Foreign Affairs has said Irish diplomats in the region are in contact with local governments.
