The nation's biggest airport shut down from about 5 am until just before 9 am because of unexpectedly heavy snowfall, a spokesman for airport operator Fraport announced.
The closure came as a shock because the sky had been relatively clear after midnight night and observers expected open runways in the morning.
“We did not count on this because we had different forecasts from the German Weather Service (DWD),” Fraport spokesman Uwe Witzel said.
Hundreds of flights were affected.
Some international flights bound for Frankfurt were being diverted to Leipzig/Halle airport in Saxony. Flights from Riyadh in Saudi Arabia, the Angolan capital of Luanda, Amman in Jordan, the Indian city of Mumbai and Tel Aviv in Israel had landed there. Lufthansa cargo flights from New York and Kazakhstan also landed at Leipzig/Halle.
By early afternoon, the airport was trying to get back up to speed.
“All three runways at Frankfurt Airport are now clear of snow and ice,” said a Fraport spokesperson. “The goal is to return to regular controlled flight operations as quickly as possible.”
The closure came after days of disruptions caused by the brutal weather, both to air traffic and also to road and rail as travellers both in Germany and around Europe struggled to reach their destinations by Christmas.
But the battle against the snow and ice turned deadly for two rail workers who were helping de-ice tracks in the Mülheim district of Cologne were killed when they were hit by a regional train.
The men, aged 40 and 41, died at the scene. They were employed by an outside firm contracted by Deutsche Bahn.
The rail operator apologized on Tuesday for the disruptions to its service and promised improvements by Christmas.
"We will run all available trains and ensure that major long-distance routes have the necessary capacity," DB manager Ulrich Homburg told daily Bild.
Meterologists from the DWD, meanwhile have warned of the danger of black ice on the roads on Tuesday in central and southwest Germany.
However, there were few accidents overnight because motorists appeared to have heeded the warnings of the past few days and either stayed home or driven with extreme caution, police said. A survey of police stations taken by news agency DPA found that even police were surprised by how quiet the roads had been overnight.
That said, a major pile-up occurred on the A40 motorway near Duisburg in North Rhine-Westphalia involving four trucks and eight cars. Four people were injured though none seriously. They accident appeared to have happened when a truck tried to change lanes, police said.