Family members saw the lifeless retiree through the windows of his apartment and the fire department was forced to break down his door around 8 pm on Sunday evening.
"Apparently the man froze to death within his own four walls," police said in a statement, adding that they are investigating details of the incident.
Germany has been gripped by a record-breaking cold snap that has already taken several lives as temperatures dropped as low as -36.6 degrees Celsius (-33.8 degrees Fahrenheit) last week.
A homeless woman froze to death in her tent on Thursday night in the state of Rhineland-Palatinate where temperatures reached -16 degrees Celsius. The 58-year-old was not prepared for the cold, police said.
Meanwhile, a 77-year-old retiree in Weimar was found frozen to death in a garden after she didn't return from an afternoon stroll last Monday.