More than 20 stations posted all-time December lows in the early hours of Thursday.
They included Hohhot, capital of the northern Inner Mongolia region, where a reading of -29.1 degrees Celsius (-20.4 Fahrenheit) broke a nearly 70-year record.
The weather office on Wednesday said five stations had logged all-time lows, including a bone-numbing -33.2˚C (-27.8˚F) in the northern city of Datong.
Authorities have issued an alert for low temperatures across a vast area of northern, eastern and southeastern China.
The brutal cold follows a summer of record-smashing heat and devastating floods across the country’s north.