Deal's Sunday morning statement expanded his earlier state of emergency declaration to cover the entire state and specified that the "state government will be closed Monday and Tuesday for all employees except essential personnel."
The governor said he was directing the Georgia Emergency Management Agency to activate the state's emergency operations plan due to the potential for dangers associated with excessive rainfall, strong winds, flooding, fallen trees and road closures.
A tropical storm watch for Georgia was upgraded to a tropical storm warning on Sunday, with meteorologists projecting the state would see the worst of Irma from Monday morning until Tuesday morning.
Irma marks Metro Atlanta's first-ever tropical storm warning, the National Weather Service said.
"On the forecast track, the center of Irma should move near or over the southwest and west coast of the Florida Peninsula later today through tonight. Irma should then move inland over northern Florida and southwestern Georgia Monday afternoon," the National Hurricane Center said in its 2 p.m. advisory.
Deal also issued an executive order authorizing 5,000 National Guard personnel to be mobilized on state active duty for response and recovery operations from Hurricane Irma.
Meanwhile, the National Weather Service issued a storm surge warning for the South Carolina coast through the northern border of Charleston County. The NWS warned of the potential for 4-6 feet of water to come ashore, strong rip currents, and winds of 30-40 mph, with gusts of 50 mph or stronger.
North Charleston Fire Chief Greg Bulanow said emergency vehicles would cease to operate with winds of 40 mph or stronger, but he does not expect that to happen.
A spokeswoman for Tennessee Gov. Bill Haslam said President Donald Trump spoke to the governor for about 10 minutes Sunday morning to offer assistance.
"[Trump] called to stress the federal government's willingness to help in any way it can when the storm reaches Tennessee," Haslam spokeswoman Jennifer Donnals told the Nashville Tennessean.
Tennessee is projected to see up to 4 inches of rain from Irma, while gusts of wind are expected to reach 40-45 mph in the eastern part of the state and 30 mph in the central part of the state. The winds could arrive as early as Monday evening.
White House press secretary Sarah Sanders said Sunday the president also spoke with the governors of Alabama, Georgia and South Carolina.
Alabama Gov. Kay Ivey warned during a Sunday news conference with other state officials that residents should brace for tree-toppling winds, especially in the eastern part of the state.
"The most recent forecast suggests that part of the state will see tropical storm conditions," Ivey said.
"The vast majority of Alabamians are only going to be affected by thunderstorm-like wind and rain conditions with some possible flash flooding," Ivey said. "But we do know that in the eastern portions of our state, they need to start preparing themselves for tropical storm conditions. We anticipate that the worst of the weather will arrive in our eastern most counties on Monday and enter others on Tuesday."