In Norway too, June and Ocotober shows a very modest increase - if any - in temperatures, while winter months (Dec - Feb) and April show a very significant warming. There is also some warming in July - August - September.
On a sidenote, May 2013 broke all previous heat records in the northern part of Norway, both montly mean and record high. All time heat records were beaten by about 2-3C
, which is huge. Karasjok recorded 30.5C on the last day of May.