"Stay inside. Stay safe", he added. The storm's eye will move through southern Georgia by Monday afternoon. All over the country, we're asking you to be prepared.
Forecasters said the hurricane will loop back around and head west by the end of the week, influenced by the development and movement of a mid-level ridge.
Overnight, Irma was downgraded to a category 2 storm, but continued to wreak havoc along the west coast.
Tropical Storm Irma is continuing to weaken as she moves toward Georgia.
The massive storm triggered evacuation orders for 5.6 million people, and made two landfalls Sunday.
Irma hit Florida after powering through the Caribbean as a rare Category 5 hurricane, the top rung of the Saffir-Simpson scale.
The National Weather Service said flooding rains were a major concern Monday, with 8 to 15 inches (20 to 38 centimeters) of rainfall predicted in southeast Georgia. John Ward, the emergency operations manager of Clay County, says crews have pulled 46 people from flooded homes by early Monday and an undetermined number are still stranded as the area's creeks and ponds are getting record flooding.
Widespread and prolonged power outages will become part of life for most Floridians over the next few days as Hurricane Irma has started to make an anticipated northern turn that will result in a destructive run through the state starting Sunday.
In South Carolina, a storm surge warning continued to be in place from the South Santee River, south to the Georgia border, the Hurricane Center said.
A report by CoreLogic, the global property data firm, found almost 455,000 Tampa Bay homes could be damaged by storm surges, the most of any major U.S. metro area other than Miami and NY. Brock said no injuries had been reported.
More than 1 million residents had already lost power by Sunday morning, and it could be days before officials can provide food and water to those struggling in the aftermath of the powerful storm.
Havana residents remained without water supplies and phone connections and schools were closed until further notice.
Fort Lauderdale police arrested nine people they said were caught on TV cameras looting sneakers and other items from a sporting goods store and a pawn shop during the hurricane.
"Due to its recent more inland push, Irma's center is now forecast to remain over Florida and then move over the southeastern United States for the duration of its existence", the weather service said, predicting it would become a tropical depression over MS by Tuesday afternoon and dissipate over adding that it should dissipate over Tennessee on Wednesday.
Media reports say a man was killed on Saturday in the Keys when his pick-up truck crashed into a tree as the storm gathered pace.
The National Hurricane Centre said the storm "should continue to lose strength and fall below hurricane intensity" during the day, as it continues its path northwards. Still a large hurricane, its tropical storm force winds extend out 415 miles, despite weakening a bit more to 100 mph.