Nordic winter is great, but tends to be to long for most of the people.
When spring finally arrives any opportunity to see the sun or enjoy warmer weather is welcomed. In Scandinavian fashion this season is called middle-season as it is impossible to know what the weather is in few hours. At least mornings and evenings can be cold.
A good advice for middle-season clothing is to always take a light weatherproof jacket with you when moving outdoors. Also a some kind of headwear and gloves are good to have with during April and May.