The Florida Department of Transportation announced Saturday that it is reopening the 14-mile stretch of Interstate 75 that was shut down due to rising river water under the highway. Officials said the Myakka River's water levels had receded enough to safely reopen the highway.

But, officials warned they may have to shut down the interstate again if water levels rise once more.

Officials had shut down I-75 from mile marker 179, near North Port and Toledo Blade Blvd. to mile marker 193, near Jacaranda Blvd, and long detours were in place.

I-75 is the main highway on the west coast of Florida and is a main route for travelers between Tampa-St. Petersburg and Fort Myers and Naples.

The Centers for Disease Control and Prevention put out a health advisory to healthcare professionals treating patients in areas affected by Hurricanes Fiona or Ian, telling them to maintain a high index of suspicion for carbon monoxide poisoning.

"Other people who may have been exposed to the same CO source may need to be identified and evaluated," the CDC said in a health advisory.

-ABC News' Eric Strauss

Four people have died in North Carolina since Friday in storm-related incidents, state officials said Saturday.

Two people died due to car accidents caused by storm conditions, one man drowned in his car and a fourth man died due to carbon monoxide poisoning from a generator.

Among those killed was a 25-year-old man who lost control of his vehicle and hydroplaned into another vehicle, a 24-year-old woman whose vehicle went off a wet road and struck a tree and a 22-year-old man who drowned when his truck left the roadway and submerged in a flooded swamp.

A 65-year-old man died Saturday from carbon monoxide poisoning from a generator running in his closed garage while the power was out. His wife was hospitalized.

“The storm has passed, but many hazards remain with downed trees, downed power lines and power outages,” said North Carolina Gov. Roy Cooper in a press release. “We mourn with the families of those who have died and urge everyone to be cautious while cleaning up to avoid more deaths or injuries.”

A flood watch remains in effect in parts of Virginia and West Virginia on Saturday as Ian’s remnants push north.

The storm is significantly weakened, but winds may still top 35 mph as rain covers the Mid-Atlantic and Northeast this weekend.

-ABC News’ Daniel Amarante

Caribbean islands such as Jamaica and Grand Cayman will start to experience the effects from the outer bands of Tropical Storm Ian within the next 24 hours, forecasts show. The islands will experience conditions such as heavy rain, possible flash flooding and storm surge.

The storm system will begin to rapidly intensify overnight into Monday before it closes in on western Cuba on Monday night.

As of 2 p.m., the sustained winds in the tropical storm remained at 50 mph as it moved west-northwest at 12 mph, the center about 265 miles away from Grand Cayman.

Hurricane warnings are in effect for Grand Cayman and western Cuba, while tropical storm warnings and watches are in effect in other portions of both islands.

As a hurricane, Ian is expected to peak at a Category 4 before weakening slightly as it looks to make landfall on the west coast or panhandle of Florida in the coming days.

There is still some uncertainty to the track Ian will take once the system enters the Gulf of Mexico.

The center of the storm and the worst of the impacts could end up heading toward the western coast of Florida's peninsula, including the Tampa area. The other possible scenario has the storm moving more due north and bringing a possible landfall along the Florida peninsula, impacting cities like Panama City and Tallahassee with more direct effects.

The storm will begin to impact the Florida keys and the southern portions of the state by Tuesday night.

-ABC News' Dan Peck