Rik, I think a wetsuit is too warm for up your way. I have a 2-3mm steamer that I wear sometimes in winter. Mostly I am OK through winter with a thermal vest under a columbia shirt. Wear lightweight fishing pants. Only time I feel cold is with the backs of my legs getting wet, but tha't particular to my yak I think. The columbia shirt and lightweight trousers are excellent sun protection all year round. Don't even think about wearing shorts or short sleeves anymore.