April weather! It could be anything and all things! I left SJPDP very near to the time you are planning - on April 12 2011. In a month of walking I only needed my wet weather gear on 3 or 4 days, and only for a part of those days. We had lovely Spring weather for most of the time.
A Dutch pilgrim I met along the way returned to the Frances in 2012 and, again, he left on April 12. He had a month of rain, wind, sleet and some snow! Two very different April caminos. He said it was no less an incredible experience, and the inclement weather heightened the sense of camaraderie amongst the pilgrims.
He plans to walk the VldP this year (in April, of course!).
So.....be prepared for wet weather and, if it doesn't find you, count your blessings! And if it does, enjoy!
buen camino