Paris France Weather In May

What is the weather like in Denmark/ Germany/ Belgium/ Netherlands/ France in March?

For a while now I’ve been wanting to bike from Copenhagen to Paris, and it so happens that I may have the opportunity to in March but I think it might be crazy to make that trip at that time of year. What is the weather there like in mid-March? Is there snow on the ground? Average temperature? Anything you can tell me would be usefull. I will roughly be following the coast I think…
Thanks