If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Tromsø: The hottest months are usually July and August, with an average temperature of 10°C, while the coldest months are January and February, with an average of -6°C. The snowiest months in Tromsø are February, January, November and December, with each month seeing an average of 58 cm of snowfall.