The first day of summer is celebrated to day. It is an annual public holiday in Iceland.
This day has its root in the Old Norse calendar used by Iceland’s settlers. That calendar only had two seasons: summer and winter. The long, dark winters were often rough on the new population of this strange island, and the brighter days of summer were eagerly anticipated. So even though the climate of late April in Iceland is normally not very summer-like, the day marks the lengthening of the days and the harsh winter being over.