More than 630 millimetres of rain has fallen over parts of the Gulf coast near Steinhatchee, in the northwest of Florida, since Thursday, resulting in county officials declaring a local state of emergency.

A front has stalled across the region, interacting with a small low-pressure system, which has a low chance of developing into a tropical system, according to the National Hurricane Center.

From late Sunday into Monday, this small area of low pressure will move northeast to the open, warm waters off the Outer Banks of South and North Carolina, producing torrential rains along with a possible tropical storm formation.

These storms could produce as much as 25mm of rain or more per hour, so localised flooding is highly possible, especially in urban areas and locations with poor drainage.

In less than twelve hours from midnight Friday to late morning Saturday, 109mm of rain fell in Hilton Head, South Carolina.

Widespread rainfall totals of 25 to 75mm are possible from northern Florida and along the southeast coast throughout the weekend, with some locations seeing as much as 110mm.

Much of north and west-central Florida is already saturated, making the region very vulnerable to flooding over the coming few days.

The National Hurricane Center is continuing to watch the area of thunderstorms over the southeast, and although the chance of tropical storm development is low, it cannot be ruled out as it moves near the southeast coast over the coming few days.