Cindy, I did a similar itinerary on Crystal around the same time last year. The weather in Geiranger and Trondheim was sunny and relatively warm. I believe we reach 72 in Trondheim. It did get colder when we headed up north, coldest weather I encountered was at the N. Cape/Honnigsvag. We actually had mild weather in Longyearbyen, it was around 45 and sunny.
Enjoy, Nancy