Spring
Spring in Helsinki is the thaw. March, April and May move from leftover winter to usable outdoor days. Snow retreats. Mud and bright afternoons can share a week.
In Helsinki the meteorological summer is June, July and August and winter is December, January and February. Come for cities and the first terraces, not for guaranteed picnic weather. A squall in Helsinki in these months is ordinary, not a ruined trip.
Read Helsinki in this stretch as its own climate, not as a generic holiday season copied from another destination.

