Eighteen people died and dozens were missing around the wine-growing hub of Ahrweiler, in Rhineland-Palatinate state, police said, after the Ahr river that flows into the Rhine rose and brought down half a dozen houses.
Eight people died in the Euskirchen region south of the city of Bonn, authorities said. In Belgium, two men died due to torrential rain and a 15-year-old girl was missing after being swept away by a swollen river.
Hundreds of soldiers were helping police with the rescue efforts, using tanks to clear roads of landslides and fallen trees, while helicopters winched those stranded on rooftops to safety.
The floods have caused Germany's worst mass loss of life in years. Flooding in 2002 killed 21 people in eastern Germany and over 100 across the wider central European region.