A state of emergency has been declared in Florida as Tropical Storm Ian heads towards the US coast and is forecast to become a major hurricane.

Governor Ron DeSantis expanded a previous warning on Saturday to cover the whole state and urged people to prepare for landfall.

It activates the state’s national guard and frees up emergency funding.

“This storm has the potential to strengthen into a major hurricane and we encourage all Floridians to make their preparations,” said the governor.

“We are coordinating with all state and local government partners to track potential impacts of this storm.”

The approaching storm has also postponed another planned attempt on Tuesday to launch NASA’s Artemis moon mission from Kennedy Space Center.

NASA executive Jim Free tweeted that a decision was imminent on whether to “roll back” the rocket back from the launch pad to its assembly building

President Biden has also declared a state of emergency in order to allow federal agencies to coordinate relief and provide help.

Storm Ian is predicted to “rapidly strengthen” on Sunday as it moves towards Cuba before hitting the Florida coast the middle of next week, according to the National Hurricane Center.

At 5am local time on Sunday it was southeast of Jamaica, with winds currently only 50mph.

It is unclear which areas of Florida will be hit the hardest but residents in Pinellas Park, near Tampa, were queuing at a Home Depot store when it opened at 6am on Saturday.

The Tampa Bay Times reported it had sold 600 cases of water by early afternoon. Electricity generators had also sold out and people were buying plywood to cover their windows.

Canada is also dealing with the effects of a tropical storm after Fiona hit the country’s Atlantic coast on Saturday.

Troops were sent to help after some houses were swept away by wind and waves, roofs torn off and power knocked out to more than half a million homes.

There was no confirmation of fatalities or injuries.