It is a good day for a walk in the park on Friday with the temperature reaching over 20 degrees Celsius in many districts.

Shanghai’s weather bureau released blue alerts for gales and a cold wave on Friday, a day when the highest temperature exceeded 20 degrees Celsius in many districts.

Blue is the lowest in the four-tier alert system in the city.

A strong cold front from the north will affect the city on Friday night, with the maximum temperature falling to 7 and 5 degrees over the weekend.

As of 4pm, it had arrived in the Yangtze River estuary, the bureau said.

The temperature will fall to zero degree on Sunday while it will be minus 4 degrees in some suburbs on Sunday morning.

The wind force is expected to be 74 kilometers per hour in the city’s coastal areas on Saturday, strong enough to blow down branches.

The cold air will leave the city on Monday and temperatures will gradually rise from 10 degrees on Monday to 15 degrees on Wednesday.

The sky will be clear over the next five days but the air will be slightly polluted on Saturday and Monday due to PM2.5 and PM10 particles blown in from the north, the Shanghai Bureau of Ecology and Environment said on Friday.