Bands of heavy rain from Isaias have lashed Florida’s east coast on Sunday, with the tropical storm strengthening slightly in the evening on its way up the eastern seaboard.

Officials dealing with surging cases of coronavirus in Florida kept a close watch on the storm that was weakened from a hurricane to a tropical storm on Saturday afternoon but still brought heavy rain and flooding to Florida’s Atlantic coast.

The National Hurricane Centre advised at 5pm local time that the storm was about 65 miles off the midpoint of Florida’s east coast, and about 410 miles south of Myrtle Beach, South Carolina.

It was strengthening slightly with sustained winds just under a category one hurricane, taking a north to north-west path.

“Don’t be fooled by the downgrade,” Florida governor Ron DeSantis warned at a news conference after the storm spent hours roughing up the Bahamas.

Upper-level winds took much of the strength out of Isaias, said Stacy Stewart, senior hurricane specialist at the National Hurricane Centre in Miami. The storm also slowed down considerably.

“We were expecting a hurricane to develop and it didn’t,” Mr Stewart said. “It’s a tale of two storms. If you live on the west side of the storm, you didn’t get much. If you live east of the storm, there’s a lot of nasty weather there.”

Florida is on the west side of Isaias.

Authorities closed beaches, parks and virus testing sites. Mr DeSantis said the state is anticipating power outages and asked residents to have a week’s supply of water, food and medicine on hand.

Officials wrestled with how to prepare shelters where people can seek refuge from the storm if necessary, while also social distancing to prevent the spread of the virus.

Isaias put another burden on communities already hit by other storms and sickness.

In Palm Beach County, about 150 people were in shelters, said emergency management spokeswoman Lisa De La Rionda. The county has a voluntary evacuation order for those living in mobile or manufactured homes, or those who feel their home cannot withstand winds.

Heavy seas near Jaycee Beach Park
Heavy seas near Jaycee Beach Park (Wilfredo Lee/AP)

“We don’t anticipate many more evacuations,” she said, adding that the evacuees are physically distant from each other and are wearing masks.

In Indian River County, north of West Palm Beach, emergency shelters were clearing out on Sunday after Isaias was downgraded to a tropical storm.

Officials told TCPalm newspapers that 38 people registered at three schools used as shelters. Those areas now must be cleaned to ensure no traces of coronavirus remain as teachers and staff report on Monday to prepare for the upcoming school year.

No one checked in with Covid-19 symptoms. Temperature checks were done at the door, officials said, and isolation rooms were designated in case anyone came in with symptoms.