“In Florida, we always prepare for the worst and hope for the best and while the exact path of Irma is not absolutely known at this time, we cannot afford to not be prepared.

“This state of emergency allows our emergency management officials to act swiftly in the best interest of Floridians without the burden of bureaucracy or red tape.

“In Florida, we know that the best way to protect our families in severe weather is to have a plan.

“I urge all Floridians to remain vigilant and stay alert to local weather and news and visit FLGetAPlan.com today as we all prepare for Hurricane Irma. We will keep monitoring and issuing updates on Hurricane Irma as it approaches Florida.”

Its latest NHC update said: “There is an increasing chance of seeing some impacts from Irma in the Florida Peninsula and the Florida Keys later this week and this weekend.

“In addition, rough surf and dangerous marine conditions will begin to affect the southeastern US coast by later this week.

“Otherwise, it is still too early to determine what direct impacts Irma might have on the continental United States.

“However, everyone in hurricane-prone areas should ensure that they have their hurricane plan in place, as we are now near the peak of the season.”

The storm is expected to be near the Cuba coast by Saturday.

AccuWeather Lead Long-Range Meteorologist Paul Pastelok said: “Irma is a serious threat for the Caribbean islands and United States.”

The major, category 4 hurricane was last located about 530miles (850km) east of the Leeward Islands.  Irma was moving 14 mph (22 km/h) west-southwestward.

After the Caribbean, it is very difficult to predict where the storm will head because there are vast differences in the long-term weather forecasts.

In some models, Irma will go back out to sea. Others show it could either hit the northern Leeward Islands or bypass them and curve towards the USA.

It has sparked widespread concern particularly among residents on the East Coast and Gulf Coast after Hurricane Harvey caused catastrophic flooding and storm surges.

Most predictions though have Irma hitting southern Florida and then heading along the eastern coast of the US and Canada, possibly hitting New York and Washington.

Fox News meteorologist Janice Dean said that Irma was coming “a little too close to comfort for the East Coast”.

Meteorological scientist Dr Michael Ventricle, at the University of Albany, tweeted: “It’s too early to know where Irma is headed. This storm could still sneak out to sea.”

Dr Ventrice has noticed a “slight” alteration in the movement of Irma, apparently moving away from the Gulf of Mexico and moving more towards the east coast.

But he added: “Things can still change.”

“The forecast models are showing quite a bit of spread in the longer term.”

After Hurricane Irma passes or hits the Caribbean, there is an even greater deal of uncertainty over where Hurricane Irma will go next.

Mr Heming said: “At this stage, we can’t rule out any impact on the US. But if there are any it will be at least a week before it happens.”

He said that it is still quite possible that Hurricane Irma could continue curving right and go back out to sea.

“We have to sit patiently and see what happens with the models before we can give a forecast with any great certainty,” he added.

The Met Office storm track map below should not be taken in isolation because it is only a ‘single solution’ from the latest run of the global model.

Irma comes after Hurricane Harvey struck Texas and Louisiana on the Gulf Coast, leading to at least 39 deaths, mass evacuations and terrible flooding.

Last week BBC Weather tweeted: “Hurricane Irma will rapidly strengthen to become a category 4 hurricane. Landfall possible middle of next week, but uncertain where.”

In a discussion last week, NHC Forecaster David Zelinsky said: “For example, the GFS shows a somewhat weaker Irma and a weaker ridge, forcing the hurricane to move slower and make a sharper turn back toward the west-northwest.

“On the other hand, the ECMWF and HWRF depict a stronger ridge and a stronger hurricane on a more southern track.”

Meteorologist Danielle Banks, from the Weather Channel, said: “Keep in mind that it is way to soon to say if its going to impact the United States, and where it will head.

“It is way too soon to say with certainty where and if this system will impact the US.”

Ag meteorologist Michael Clark tweeted: “Folks on SE coast need to keep a very close eye on #Irma as it has potential to be a very strong hurricane. EPS members show landfall.”