The storm is expected to gain hurricane status by Monday night or Tuesday as its center moves over the Yucatan Channel and then crosses the Gulf of Mexico, nearing the Florida Panhandle coast by Wednesday.
Meanwhile, Tropical Storm Leslie continues its easterly path across the central Atlantic with maximum sustained winds of 60 miles per hour.
After reaching land, Michael is expected to travel northeast at hurricane strength as it passes over Georgia.
Scott had already announced Sunday morning he would declare a state of emergency due to the storm.
He urged Floridians to get prepared for the storm and said he has activated 500 members of the Florida National Guard.
"Michael expected to become a hurricane very soon", the National Hurricane Center announced in its 8 a.m. bulletin.
Michael is expected to gradually strengthen and lift northward into the Gulf of Mexico on Monday, becoming a hurricane Monday night into Tuesday, according to a press release from the National Weather Service Charleston.
The storm moved north on a path between Cozumel in southeastern Mexico and the western tip of Cuba, the Miami-based hurricane center said.
The Walking Dead Season 9 Premiere Ratings Lowest Since 2010
AMC doesn't release numbers for the streaming service, though, so we don't know for sure how many people watched it there. The Hollywood Reporter reports that the premiere achieved a 2.5 rating among adults ranging from 18-49.
The hurricane centre warned that the storm could produce up to a foot (30 centimetres) of rain in western Cuba, potentially triggering flash floods and mudslides in mountainous areas.
Michael could make landfall as early as Wednesday morning (as predicted by the hurricane center) or as late as Thursday morning, Weather Underground meteorologist Jeff Masters said.
A hurricane watch has been issued for north Florida and a tropical storm watch has been issued for parts of the western coast of Florida, including Tampa.
Hurricane-force winds extend outward up to 35 miles (55 km) from the center and tropical-storm-force winds extend outward up to 175 miles (280 km).
More than 45 percent of the nation's refining capacity is located along the U.S. Gulf Coast, which also is home to 51 percent of total U.S. natural gas processing capability.
In the United States, a storm surge watch has been issued from Navarre, Florida to Anna Maria Island, Florida. "Additional strengthening is indicated through 72 hours when the storm is forecast to be near the northern Gulf coast".
When the storm moves ashore, it will probably be a Category 1 storm, with winds between 74-95 miles per hour, said Frank Strait, senior meteorologist for the private forecasting firm AccuWeather.
The next tropical storm name on the hurricane center's list is Michael.