The May Day holiday from Wednesday to Saturday will be mostly dry and cloudy with temperatures in the 20s.
However, Monday and Tuesday will be rainy due to moisture from southwest China.
Monday is likely to have a dry start but will soon turn overcast with thundershowers in the afternoon. On Tuesday the rain will weaken to drizzle.
The mercury on Monday and Tuesday will range from 15 to 20 degrees Celsius.
Starting from Wednesday, it will become warmer with the high increasing to 22 to 24 degrees on the weekend.
Skies will be cloudy between Thursday and Saturday.
About 2.2 million people will leave town by train from April 30 to May 4 for the Labor Day break, 5 percent more than last year, according to Shanghai Railway Station.
The peak is expected to be May 1 as more than half a million depart.
The city’s three railway stations have prepared 101 extra trains for destinations across China.
Meanwhile, at Shanghai South Railway Station, high-speed trains going to Jinhua and Kaihua in Zhejiang Province will start operation from May.
Before that, people could only take coaches to get to Kaihua.