Trondheim sits at 63 degrees north, almost on the same line as Anchorage, and the seasons feel it. The best time to visit is May to August, when the days are long, the city's outdoor cafés open up, and ferries run out to Munkholmen. June and July see near-endless daylight — sunset at midnight is normal, and the sun barely sets at the summer solstice — though the city does not go fully into the midnight sun (you have to head further north for that). Average July highs are around 17 °C.
September brings autumn colour and emptier streets. Winters are long, dark and snowy: November to February days are short and cold, with the sun barely above the horizon, but the city looks beautiful under snow and the chance of seeing the northern lights from town is reasonable on a clear winter night. Olavsfest at the end of July, around the feast of Saint Olav, is the city's biggest event — concerts, food markets, and processions centred on the cathedral.