Fifty-eight of the fatalities were in Germany, with Chancellor Angela Merkel calling the situation a "catastrophe" as she expressed solidarity with those affected by the flooding.
She said: "I grieve for those who have lost their lives in this disaster."
The Kyll river has overflowed its banks in Erdorf and flooded parts of the village.
In Belgium, nine deaths have been reported.
The dead included at least 30 in North Rhine-Westphalia state and 28 in Rhineland-Palatinate state to the south.
Among the worst-hit German villages was Schuld, in the Rhineland-Palatinate district of Ahrweiler, where several homes collapsed and up to 70 people remained unaccounted for.
A flood-affected area in Schuld, Germany
Dozens of more people were trapped on the roofs of their houses awaiting rescue. Authorities used inflatable boats and helicopters, and the German army deployed 200 soldiers to assist in the rescue operations.
They were hampered as phone and internet connections were down in parts of the region.
Chancellor Merkel pledged everything would be done to find those still missing.
Several homes collapsed due to severe flooding in Ahrweiler, Germany
The full extent of the damage across the region was unclear after many villages were cut off by floodwater and landslides that made roads impassable.
Many of the dead were discovered after floodwaters began to recede again.
Four people died in separate incidents after basements were flooded in Cologne, Kamen, and Wuppertal, where authorities warned that a dam could burst.
Rhineland-Palatinate (Rheinland-Pfalz) premier Malu Dreyer said: "It's a catastrophe. There are dead, missing and many people still in danger. All of our emergency services are in action round the clock and risking their own lives."
Heavy rain and severe flooding caused six homes to collapse in Schuld in the district of Ahrweiler, in Rhineland-Palatinate, Germany
Video footage from the German spa town of Bad Neuenahr showed damaged properties, cars and trucks strewn across streets - some perched precariously on walls and fencing, and fallen trees and floating debris.
In Belgium, among the nine fatalities were two men who died due to the torrential rain. A 15-year-old girl is missing after being swept away by a swollen river.
Around 10 houses collapsed in Pepinster after the river Vesdre flooded the eastern Belgian town and residents were evacuated from more than 1,000 homes.
The city of Hagen has declared a state of emergency.
Some 200,000 properties were without electricity in Germany, said Westnetz, the country's biggest power distribution grid company, adding that many substations cannot be reached for repairs because roads are still blocked.
Weather experts said that rains in the region over the past 24 hours had been unprecedented.
The Greens political party blamed the floods on global warming, with its parliamentary leader Katrin Goering-Eckardt telling RTL/NTV television: "This is already the impact of the climate catastrophe and this is another wake-up call to make us realise: this is already here."
Residents have had to be evacuated in some parts of western Germany.
A 63-year-old resident told SWR television: "I've never experienced a catastrophe where the river burst its banks in such a short space of time."
It comes after the German weather service DWD issued an extreme weather warning for parts of three western states yesterday, and the army was deployed to help stranded residents, transport evacuees and fill sandbags as rivers burst their banks.
Two firefighters died in the Sauerland region, northeast of Bonn, on Wednesday.
A woman wades through the floodwater in Gross-Vernich in North Rhine-Westphalia
One had drowned and a second collapsed after a rescue operation, according to the DPA news agency.
Hagen, a city of 180,000, declared a state of emergency on Wednesday after the Volme river burst its banks.
Floodwaters caused the lifts to fail in a hospital, and a care home had to be evacuated.
Residents were also told to leave a district of the regional capital Duesseldorf, a major business centre.
The deluge of rain and flooding has disrupted rail, road, and river transport, with shipping suspended on the Rhine river.
Further rainstorms are expected to hit southwestern Germany and could continue until Friday night, forecasters have warned.
"We see this kind of situation only in winter ordinarily," Bernd Mehlig, an environment official from North Rhine-Westphalia, the most affected region, told broadcaster WDR. "Something like this, with this intensity, is completely unusual in summer."
The torrential downpours also extended into France, Luxembourg, and the Netherlands too.
Flooding in 2002 killed 21 people in eastern Germany and more than 100 across the wider Central European region.