Some cities in Northern Sweden and their yearly average low/high:

Kiruna: -8.1 to 1.8 Luleå: -1.5 to 5.9 Umeå: -0.8 to 6.7

Luleå and Umeå both have Universities and populations of ~45k and ~80k respectively. Kiruna is a mining town.

I lived in Umeå for a few months, it's actually pretty pleasant.