0400 GMT December 14, 2017
Tens of thousands of Floridians were hunkering down in shelters for a direct hit from the monster storm, after more than 6.3 million ― nearly a third of the state's population — were ordered to evacuate, ALJAZEERA reported.
For those still at home, it was already too late to escape the wrath of what could be the worst hurricane in storm-prone Florida.
More than 170,000 homes and businesses in Florida have lost power and the center of Irma is about 140km southeast of Key West.
Florida Power and Light said on its website that more than half of those outages were in the Miami-Dade area, where about 600,000 people have been ordered to evacuate.
"If you have been ordered to evacuate anywhere in the state, you need to leave right now. Not tonight. Not in an hour. Now. You are running out of time to make a decision," Governor Rick Scott said hours before wind gusts began to lash the island chain known as the Florida Keys.
At North Collier Regional Park, a designated shelter just outside the city of Naples, anxious evacuees prayed they and their loved ones would remain safe when the storm made landfall.
"All we wanted to make sure is to feel safe and whatever happens we just have to start I guess from the beginning," Viviana Sierra said.
MacDill Air Force Base, the military installation home to US Central Command, issued mandatory evacuation orders with the eye of the storm expected to pass over its home city of Tampa early Monday. The Kennedy Space Center was also closed.
The White House said President Donald Trump, Vice President Mike Pence and their cabinet were briefed on Hurricanes Irma and Jose, with Trump warning on Twitter that this is a storm of enormous destructive power.
After blasting through the nearby Cuban coastline, Irma weakened from a maximum-strength Category five to a Category three storm, but then strengthened again to a Category four, with 210km/h winds, as it approached south Florida.
With near-hurricane force winds lashing the Florida Keys starting around 8:00pm (01:00GMT), the Miami-based National Hurricane Center (NHC) warned that Irma is forecast to re-strengthen as it approaches mainland Florida.
There was a serious threat of flooding from storm surges of up to 4.5 meters along Florida's west coast — enough to cover a house.
At least 25 people have been killed since Irma began its devastating march through the Caribbean earlier this week.
Terrified Cubans who rode out Irma in coastal towns after the storm made landfall on Friday on the Camaguey archipelago reported ‘deafening’ winds, uprooted trees and power lines, and blown rooftops.
There were no immediate reports of casualties, but officials reported ‘significant damage’. A total of 1.5 million people were evacuated.
"When Irma eventually hits land it might be a Category three, which is significantly less than what was predicted," said Al Jazeera's Alan Fisher, reporting from Miami.
"But that is still a major storm and still could cause significant destruction across Florida."
While Miami would likely ‘escape the worst’, Key West ‘is going to be hammered’, Fisher said.
"This was a city that was prepared for the worst and has been preparing since Monday to what might come their way,” Fisher said.
Michael Hernandez, adviser to Miami's mayor, told Al Jazeera: "We've taken unprecedented measures to protect our residents.
"We feel that we have done all that we can ... whether this storm hits us as a Category five, four, or what they're saying since it's moved away ― a Category one or two. It doesn't matter. We made the right call."
DUTCH DEFENSE MINISTRY/AFP/GETTY)