Thursday holds key to winter
Shanghai's air quality improved on Wednesday afternoon following a wave of moderate pollution, while Thursday's temperatures will decide whether winter has officially arrived.
The city's air was moderately polluted by PM2.5 particles blown from northern China and the air quality index hit 199 at 9am, almost reaching the heavily polluted level of 200, according to the Shanghai Environmental Monitoring Center.
The index then dropped from noon and stood at 94 as of 5pm on Wednesday, or good level, the center said.
Air quality is forecast to be good to excellent on Thursday, and that will continue on Friday and Saturday, it added.
Thursday should be cloudy to overcast, with temperatures between 13 and 6 degrees Celsius and stronger winds, the Shanghai Meteorological Bureau said.
Winter becomes official when the average temperature is below 10 degrees for five consecutive days after lidong, or the start of winter according to the Chinese calendar.
As of Wednesday, four days had met the standard so Thursday's temperature will decide if winter has arrived, forecasters said.
A weak cold front is on the way and Friday's highest temperature will plummet to below 10 degrees, according to the bureau.
It should be overcast to cloudy on Friday.
Temperatures will rebound are the weekend, reaching highs of 11 to 15 degrees and lows between 5 and 7 degrees, forecasters said.
The weekend should be sunny to cloudy.