The 1.8 ton British bomb was found in the Rhine River in the city of Koblenz. It was discovered last week alongside another bomb dropped there by U.S. forces during WWII, after Rhine's water level fell due to lack of rain.
Everyone living within a radius of just over a mile is being moved out before the bomb is moved or defused.
That includes several nursing homes, two hospitals and a prison. Train and road traffic in the area, some 130 kilometers northwest of Frankfurt, will come to a halt.
Experts are planning to head in Sunday morning.
The Associated Press contributed to this report.