Hurricane Irma to 'devastate the United States' and remains incredibly dangerous, Fema warns

'There is a lot of certainty in this forecast'

Large parts of the Turks and Caicos Islands have already been destroyed (AP)

Hurricane Irma will "devastate the United States" and remains "incredibly dangerous", the country's Federal Emergency Management Agency (FEMA) has warned.

US officials are currently making hurried preparations for the storm which is expected to make landfall in Florida as early as Saturday morning.

Speaking at a news conference on Friday, FEMA Administrator Brock Long warned that as many as 100,000 people may need shelter and whole parts of the state could face days without electricity.

Speaking at FEMA headquarters in Washington, Mr Long repeated the advice being offered to people who were at risk of being in the storms’s potential path - get out now.

He said no one in Florida had experienced a storm with the intensity of what was now bearing down on the state. He said there is “a lot of certainty in this forecast” showing Irma making landfall somewhere in Florida this weekend, and the winds and storm surge from the storm have the potential to be devastating.

Mr Long said those in low-lying areas who've been told to evacuate “need to get out and heed the warning”.

More than 8,000 FEMA staff have been deployed to prepare for Irma and help with the continuing recovery effort from Hurricane Harvey, which caused massive flooding in southeastern Texas last week, he said