What's the weather and climate like in Belgium, Holland, France and Germany in May?

May is very warm. Generally speaking, it should be sunny. However, due to the abnormal climate in recent years, it is also possible that sometimes there will be some cold or rainy weather. It depends on where Germany is. Although Germany is not big, the differences between different places are quite large. Generally speaking, if you are in the south, you can bring more short-sleeved T-shirts, one or two long ones and a coat, but in the north, the number of T-shirts should be reversed. France should be warmer (more southerly) than Germany, and Belgium and the Netherlands should not be much worse than Germany.