Authorities in Bermuda opened shelters and closed schools and offices on Friday ahead of Fiona. Premier David Burt sent a tweet urging residents to "take care of yourself and your family. Let's all remember to check on as well as look out for your seniors, family and neighbours".

The Canadian Hurricane Centre issued a hurricane watch over extensive coastal expanses of Nova Scotia, Prince Edward Island and Newfoundland. The US National Hurricane Center said Fiona should reach the area as a "large and powerful post-tropical cyclone with hurricane-force winds".

The centre said Fiona had maximum sustained winds of 215km/h late on Thursday. It was centred about 315 kilometres west of Bermuda, heading north-northeast at 33km/h.

Hurricane-force winds extended outward up to 185km from the centre and tropical storm-force winds extended outward up to 445km.

Fiona so far has been blamed for at least five deaths -- two in Puerto Rico, two in the Dominican Republic and one in the French island of Guadeloupe.

Hurricanes in Canada are somewhat rare, in part because once the storms reach colder waters, they lose their main source of energy. and become extratropical.

Before reaching Bermuda, Fiona caused severe flooding and devastation in Puerto Rico, leading US President Joe Biden to say on Thursday that the full force of the federal government is ready to help the US territory recover.

More than 60 per cent of power customers remained without energy on Thursday and one third of customers were without water, while local officials said they could not say when service would be fully restored.

As of Friday, hundreds of people in Puerto Rico remained isolated by blocked roads five days after the hurricane ripped into the island.

Australian Associated Press