It is cold in the Arctic, but thanks to the Gulf stream that brings warm water along the Norwegian coast. It is cold but not too cold here in Troms. Still, there is plenty of clean and cold air for cooling down the servers. It is free and sustainable all year around.
The coldest average in January is -4°C. During this the polar nights of December and January, the sun stays below the horizon. July is the warmest month with an average temperature of 12°C. The midnight sun shines 24/7 in June and July.
The warmest weather recorded was 30°C in July 1972 while the coldest record was -18.3°C in January 1987 for the city of Tromsø. (data from www.yr.no)