Olomouc has the central European pattern — warm summers, cold winters, mild shoulder seasons. May to early October is the comfortable window: warm enough to sit on the squares with a beer, dry enough to enjoy the surrounding countryside. July and August can hit 30°C but Olomouc rarely feels uncomfortably crowded.
Late November to early January is the Christmas-market season, when Horní náměstí fills with wooden stalls, mulled wine, and trdelník vendors. September brings the International Organ Festival, with concerts every weekend in the Church of Saint Maurice. February is bleak; March can be muddy. Snow is possible from December through February.