April is the changeful spring in Beijing, so both of the sayings are right. If you come to Beijing in early April, there will be occasional sandtorm and rainfall, so the temperature is cool but much better than in winter. Usually, a long-sleeved shirt windproof jacket is ok. After the mid of April, the climate will be warmer and warmer day by day. You will find the most of young ladies dressing jeans skirt. There will be seldom raifall during this period. Hope this helps!