Shanghai has had its warmest December and January period since temperatures were first measured in 1873, according to Shanghai Meteorological Bureau.
Forecasters said this winter could be the warmest since record-keeping began.
The average temperature was 10 degrees Celsius last December, 2.7 degrees higher than usual for the month.
In January, the average temperature was 7.5 degrees, which ties the record set in 2014.
This year's first solar term lichun, or the traditional beginning of spring, falls today. Meteorologically, however, it requires five consecutive days with the average temperature above 10 degrees for spring to officially begin.
Usually, Shanghai enters spring in March.
Forecasters said the city would start to have warmer days from today, with temperatures ranging from 5 to 11 degrees until Monday.
Drizzle is expected to hit the city today and tomorrow. Sunday and Monday will be cloudy.