Many prefer to complete the walk in Spring or Autumn. Summer has the most walkers and some very hot weather. I believe you can expect all conditions during the walk, though the weather is more stable in the Summer. If you are on the route already why not check back to this site to get the current forecast for the main towns on the way.
I hope the weather treats you well! Here is a traditional Irish blessing to help you on your way …
May the road rise to meet you
May the wind be always at your back
The sun shine warm upon your face
The rains fall soft upon your fields
And until we meet again,
May God hold you in the hollow of his hand.
Santiago de Compostela