The depression's maximum sustained winds were near 35 mph (55 kph) with some strengthening expected during the next two days. Forecasters said it could become a tropical storm later in the day or overnight.
As of 5 a.m. EDT, the depression was centered about 155 miles (245 kilometers) west-southwest of Key West, Florida, and was moving west near 9 mph (15 kph).
The depression was expected to bring 3 to 5 inches of rain over the southern Florida peninsula and the Florida Keys through Wednesday that could cause flooding and flash flooding. The system is expected to impact the eastern Gulf/Florida Panhandle region later this week.