What will the weather be during March 24 through April 3 Beijing and Shanghai?

In BJ, the temperature may range from 45 F to 65 F at that time. It will be cool and comfortable. There will have many sunny days.
In Shanghai: It will be 60 F to 80 F. It will become warmer than BJ.
This period is suitable for the sightseeing. About the clothes, you can prepare jackets, T-shirts, long sleeves and jeans.