Pamplona

This Friday I head to Pamplona for the WIC race on Saturday and the road racing on Sunday. The WIC race is 30km for the women and 42km for the men. The course is 1200 meters with a turn at each end and apparently a slight rise. I didn't get the chance to race in Pamplona last year so this will be my first ever visit to the city. Quite a few national teams will be there, including Colombia so there should be some real top class racing. Had a quick look at the long range weather forecast and one site I looked at is predicting rain with the chance of thunder storms on Sunday. Then another site said Saturday afternoon/evening chance of rain and thunder. What is up with the weather?