Debby intensified into a hurricane late Sunday as it approached Florida's Gulf Coast, threatening to deliver record-breaking rainfall and major flooding, leading to evacuation orders.

The hurricane, classified as Category One on a five-stage scale, rapidly strengthened due to the unusually warm waters of the Gulf of Mexico. It is expected to hit Florida's Big Bend region around midday Monday.

The National Hurricane Center (NHC) warned of life-threatening storm surges along Florida's Gulf Coast, with water levels potentially rising 6 to 10 feet (1.8 to 3.0 meters) above ground in some areas.

The NHC also predicted catastrophic flooding with "potentially historic heavy rainfall" as Debby moves northeast across Georgia and South Carolina in the coming days.

Governor Ron DeSantis, during an emergency briefing, highlighted the risk of significant flooding, especially in north-central Florida, and emphasized the need for residents to finalize their emergency preparations immediately.

As of 11:00 pm (2100 GMT), Debby was located about 100 miles (160 kilometers) west of Tampa, with maximum sustained winds of 75 miles per hour and moving north at 12 miles per hour.

Mandatory evacuations were ordered for parts of Citrus County, Florida, with eight other counties under voluntary evacuation orders. Paul Hasenmeier, Hernando County fire chief and public safety director, urged residents to take the situation seriously, warning of rising waters as the storm passes.

Debby is expected to bring 6 to 12 inches of rain to parts of Florida and up to 20 to 30 inches in coastal Georgia and South Carolina before the end of the week, according to the NHC.

In response to the storm, the governors of Georgia and South Carolina have declared a state of emergency. NHC Deputy Director Jamie Rhome warned of "multiple days of very, very heavy rainfall," potentially leading to severe flash flooding in areas that typically do not flood.

President Joe Biden approved an emergency declaration for Florida on Sunday, allowing for expedited federal aid. Governor DeSantis has activated the state's National Guard, with 3,000 service members on standby to assist with storm response.