Hurricane Isaias lashed the Bahamas as it churned toward Florida, bringing new dangers to a US state suffering record deaths from an unrelenting coronavirus outbreak.

The category one storm, packing winds of up to 136km/h an hour, gained strength after sweeping over the Dominican Republic.

As of 7am this morning, it was an expansive storm, moving northwest at a speed of 23km/h mph, kicking up heavy squalls and whipping the Bahamas, as well as the Turks and Caicos island chains with strong winds, the Miami-based National Hurricane Center said.

"Hurricane conditions and dangerous storm surge are expected in portions of the Bahamas through Saturday, and Hurricane Warnings are in effect," it added.

Hurricane warnings were up across the low-lying Bahamas while parts of Florida's east coast, including Palm Beach, the location of President Donald Trump's Mar-a-Lago resort, were under a hurricane watch.

Florida could start feeling the effects of the storm by late this evening, according to the NHC.

The body warned Isaias will produce heavy rains and "potentially life-threatening flash and urban flooding", especially in low-lying and poorly drained areas across southern areas.

Florida governor Ron DeSantis signed an emergency declaration for counties on the exposed Atlantic coast.

But a slight shift westward in the storm's trajectory raised hopes that Florida would be spared a direct hit.

Mr DeSantis said it was too early to open shelters, but urged residents to stock up on enough water, food and medicine to last a week.

Bahamas Prime Minister Hubert Minnis had relaxed strict stay-at-home orders imposed because of the coronavirus to allow residents to prepare for the hurricane.

"I beg you, do not use this period for hurricane preparation to go socializing and visiting friends or family," Minnis said at a news conference.

"If you do not need to be out, please, please, STAY AT HOME! We are in the midst of a pandemic and if we do not act responsibly, the consequences could be dire," he said.

It is the Bahamas' first hurricane since Dorian, a maximum strength Category 5 storm last year that devastated two islands, pummeling them for three days.

The hurricane caused widespread damage in the Dominican Republic

Isaias caused widespread damage in Puerto Rico, downing trees and electric lines and inundating houses as it cut a path through the island.

In Florida, the concern was that if Isaias does hit, it would cause havoc at a time when hospitals are flooded with a surge of Covid-19 cases.

On Friday, the state reported another 257 deaths, setting a fourth consecutive single day state record and pushing its virus death toll to 6,843.

Florida's coronavirus testing centres, meanwhile, were closed on Thursday and will not reopen until they get the all-clear.

The state's emergency management division explained that these centres are housed in tents and could not withstand tropical force winds.

Meanwhile, the hurricane may also delay the return of US astronauts from the International Space Station.

Bob Behnken and Doug Hurley are scheduled to 'splashdown' on Earth tomorrow.