Kristiansund sits at roughly 63°N — well north enough for long summer days but south of the Arctic Circle, so no midnight sun and no polar night. In June and July the sun sets late (around 23.00) and rises very early; there are effectively 20 hours of daylight at midsummer. This is the best time to visit: the harbour is busy, the Atlantic Ocean Road is at its most dramatic, and the coast is accessible by boat.
Summer (June to August) is the peak season. The weather is mild rather than warm — average July highs around 17°C — and rain is frequent; the west Norwegian coast gets a lot of precipitation year-round. Pack for wind and occasional showers even in July. Ferry and boat trip bookings fill up; arrange accommodation in advance if visiting in July.
Spring (May) and autumn (September) offer quieter conditions, lower prices, and interesting light. The sea fishing is good in spring, and September brings clear days with the low-angle light that photographers favour.
Winter is grey and wet more often than it is snowy. There is no particular draw in December or January unless you are connecting to somewhere else. Northern lights are theoretically visible on clear nights in autumn and winter, but Kristiansund is far enough south that the displays are less reliable than in Tromsø or Bodø.
The Operaen i Kristiansund festival, held each January, is the oldest opera festival in Norway and draws performers and audiences from across Scandinavia — an unlikely but genuine cultural event in a fishing town.