Colmar can be visited at any time of year — but late November to late December is the headline season, when the city's five Christmas markets fill every old square and the streets glow with garlands of fir and lights. It is the most magical and also the most crowded period; book accommodation many months ahead. The wine harvest in late September and October is the other peak, when surrounding villages host their own fêtes.
Summer is warm and dry, sometimes very hot in July and August; the canals and outdoor terraces are at their best. Spring and early autumn are quieter and arguably the best balance — open vineyards, manageable crowds, mild light. Winter outside the Christmas weeks can be raw and grey but tickets to the Unterlinden are easy and rooms cheap.