Irma: Most powerful Atlantic storm ever heading for US

Hurricane Irma is now officially the most powerful storm ever recorded in the Atlantic Ocean.

It has strengthened to a Category 5 storm, the highest possible ranking on the hurricane intensity scale, with winds up to 185 mph (295 kph).

Four other storms in the overall Atlantic region have had similar wind speeds, but they have been in the Caribbean Sea or the Gulf of Mexico where the warmer water means tropical cyclones are more likely. 

Climate change is the leading factor behind the storm's size, according to Dr Jeff Masters of forecasting service Weather Underground.

The open ocean is not usually warm enough for hurricanes to form, but the Atlantic is currently one degree Celsius warmer than usual, fuelling Irma's unprecedented intensity. 

The hurricane has just hit the island of Barbuda, where the population of less than 2000 has been told not to leave their homes.

Other Caribbean islands, such as Antigua and the British Virgin Islands, are in the path of destruction.

Irma is predicted to then make its way through Haiti and the Dominican Republic, Turks and Caicos, the Bahamas and Cuba.

It will potentially hit Florida before this weekend.

US President Donald Trump has declared a 'pre-landfall' state of emergency, and mandatory evacuations have been ordered for the Florida Keys.

The entire state is on high alert, with many Floridians stocking up on food and water and pre-emptively driving to the mainland, The Washington Post reported.

The superstorm comes as the United States is still recovering from Hurricane Harvey, which brought record-breaking rainfall to Texas and left at least 60 dead.