The storm flooded homes and business districts and closed multiple roads.
The National Hurricane Center issued its last advisory on the storm at 5 p.m. EDT. Debby was about 180 miles east of St. Augustine, moving east at about 13 mph with maximum sustained winds of 40 mph. All weather watches and warnings have been lifted.
Rain diminished during the day Wednesday after inundating some areas with totals topping 25 inches. Jacksonville received more than a foot of rain while other areas saw 4 to 8 inches.
Jacksonville's flash flooding led to numerous water rescues and reports of water entering homes Tuesday evening, The Weather Channel said.
Many coastal areas reported storm-surge flooding and gusty winds.
One to 2 feet of rain flooded parts of northern and central Florida as Debby drenched much of the state for four straight days.
Wakulla County -- a mostly rural Florida Panhandle area on the Gulf of Mexico, 30 miles south of Tallahassee -- reported more than 26 inches of rain Tuesday, as Debby sat nearly motionless offshore. County officials rescued residents by boat and helped people evacuate livestock trapped by the rising waters.
Live Oak, 80 miles east of Tallahassee, had waist-deep water, The Weather Channel said. Live Oak is surrounded on three sides by the Suwannee River, made famous by 19th century songwriter Stephen Foster.
The storm spawned nearly two dozen tornadoes, which downed power lines, damaged homes and businesses and flipped tractor-trailer trucks.
A 32-year-old mother of three was killed Sunday in a tornado in Venus, 80 miles east of Sarasota Springs. Heather Town was found about 200 feet from her home clutching her 3-year-old daughter, who survived, the Highlands County Sheriff's office reported.
The woman's two other daughters were not home when the tornado struck.
Debby was the earliest-ever fourth-named Atlantic storm, beating Hurricane Dennis, named July 5, 2005.
In an average year, the fourth-named storm occurs by Aug. 23, The Weather Channel said.