what is the weather in beijing in march and april.

Weather in March is changeable and still dry and windy. The average temp at that time will be 6-8C. A thick sweater and a jacket are necessary. Due to the big difference of the temperatures, you may also prepare Long John for cold night.
During April, it is generally pleasant, but the sandstorm or rain may happen then. The average temp is about 12-14C. A waistcoat or jacket is needed. You'd better pay attention to the weather forecast in case the sudden rain happens.