The weather at the Kuikka cabin is for a (very local, rather) continental climate. In April, there is still snow and the temperature is around 0°C. In May, the snow is melting (0-15°C). But remember that the temperature during the nights is still below zero. In July and August it can be very hot (30°C), and even hotter (35-40°C) in the photo hides.
However, the weather can chance at once, so that you might feel chilly or even cold in the summer, too. You have to be prepared for everything. Sunshine and rain showers alternate from one moment to the other. Also check the website www.yr.no, give in Kuhmo as location if needed.