If you don’t like walking in rainy conditions but you want to stay away from very high temperatures too, there are two months we can recommend: June and September.
If you want simply to avoid the colder months you can start walking from mid April/May (10-15 C) and the season continues until approximately end of October (10-25 C).
Most pilgrims will be walking in July and August (simply because of the summer holidays). Don’t underestimate the high temperatures. It’s really not okay to be walking after 1 or 2 pm in those months. Learn from the locals: they do the siesta during the warm hours of the day for a good reason!
This post is also available in: Dutch