Hi Larry,
Welcome to the Forum and I hope you get plenty of help.
Your question regarding weather in the mountains starting from Roncesvalles. Note that the Pyrenees are not the only mountains you will be in, nor are they the highest - the highest point is in the Montes de Leon after Astorga.
Regarding the Pyrenees in mid April I think you can get sunshine, rain, rain and low cloud or any combination plus cold wind. I think you will appreciate that in mountainous areas the weather can be very unpredictable and changeable. In the Montes de Leon which you should reach approx. 10 days before Santiago you could experience similar conditions to the Pyrenees - in the 2nd half of may this year there were days when pilgrims could get together and eat their meals outside in comfort, other days were cold and pilgrims were lashed by wind and rain all day. Whatever the weather in the mountains, even as you approach Santiago through Galicia you can get heavy rain at any time among periods of sunshine. Hope for the best but prepare for the worst.
Buen Camino,
Brendan