Mohe - known as "China's North Pole" - is in the province of Heilongjiang, close to the Russian border.
On Sunday, its local meteorological station recorded a record-low temperature of -53C (-63F) at 7am. The previous coldest temperature on record in the city was -52.3C, in 1969.
However, the temperature is still shy of China's national record.
The coldest temperature ever recorded in China is -58C, in the city of Genhe, Inner Mongolia in December 2009.
By contrast, the lowest temperature recorded in the UK is -27.2C, set in different parts of Scotland in 1895, 1982 and 1995
Mohe is no stranger to cold weather: China Daily says the city is regarded as the coldest in China, and that its winter period "usually lasts eight months".
As a result, it attracts tourists throughout the year with its "North Pole", ice and snow parks, and skiing venues. In previous years, it has also hosted winter marathons.
This time of year, it is common for the city to see average temperatures of -15C.
In the past week, China's meteorological authority issued alerts for plunging temperatures and cold winds in the region.
The Xinhua News Agency said a number of areas in the Greater Khingan mountain range, which spans Inner Mongolia and Heilongjiang, saw new record low temperatures over the weekend.
Since Friday, temperatures dipped below -50C in Mohe for three consecutive days, which outlets have said is unprecedented.
Beijing News reported on Friday that coal consumption has increased by a third in the city, as the cold weather bites.
Car companies also told the paper they had taken advantage of the cold to test the braking performance of vehicles.
One resident told Kanji Video that his hands had been numb within 10 seconds of stepping outdoors, but that he had seen very few other people around.
"It becomes hazy about 100m in front of you, you can't see anyone," he said.
A tourist, surnamed Li, told Beijing News that he had made a special trip from China's southernmost province, Guangdong, to experience the extreme weather.
"I didn't expect it to get below -50C this year, it was quite a surprise," he told the paper.
Meanwhile, the official broadcaster, CCTV, showed a journalist breaking an egg on an outdoor surface - causing the egg to freeze within seconds.
More generally, the media are paying tribute to essential workers - including police officers, firefighters, soldiers and street cleaners - who are continuing to work outdoors during the cold.
China has seen record temperatures over the past year, for heat as well as cold.
Earlier this month, the Xinhua news agency said that the country had recorded the hottest summer and autumn in 60 years, with multiple cities breaking records.
Climate change increases the likelihood of extreme weather generally - and while scientists agree global temperatures are rising, that doesn't mean we will stop having periods of very cold weather.