Temperatures in Hulunbuir, in the Inner Mongolia autonomous region, hit a record high of 44.1 C on Wednesday, resulting in dozens of people seeking medical assistance for heatstroke.
The previous record in the city, one of China's coldest, was 42.5 C.
Temperatures were forecast to remain high on Thursday, before beginning to ease from Friday onward.
"The locals are experienced at dealing with extreme coldness, but not the heat," said Ren Dongwei, an emergency doctor at the city's People's Hospital.
"This lack of awareness may easily lead to heatstroke."
The city has had a run of hot, dry weather for almost two months, leading to droughts and locust infestations.
One local herdsman told Xinhua News Agency that the topsoil was dry to a depth of one foot, an occurrence he described as "extremely rare".
Located in the northeast of the Inner Mongolia autonomous region at roughly the same latitude as cities such as Paris and Quebec, Hulunbuir is a favorite among tourists for grassland sightseeing. It is also renowned for its cold air, attracting visitors who want to escape the summer heat.
