Wheather in late April / early May for travel to Beijing-Xian-Luoyang-Shanghai-Hong Kong ?

The weather will be warm at that time, it is just a bit crowded in May Day holiday. Still need to bring a warmer jacket. Still cool in Beijing and Xian, especially when it rains. The temperature in early May in Beijing, about 13-26 degrees, may be 30 degrees if the weather is good. Temperature difference during a day in Hong Kong is much smaller.