The best time to visit Bremen is May to September, when temperatures are warm (18–25°C), outdoor beer gardens and riverfront terraces are in full swing, and the city's parks and Bürgerpark are at their most inviting.
Spring (April–May) is quietly excellent — fewer tourists than summer, cherry blossoms in the Rhododendron Park, and comfortable walking weather. The Rhododendron-Park's famous 'Rhodo Week' in May draws visitors from across Germany.
Summer (June–August) is the peak season. The Weser promenade and Schlachte embankment buzz with life, outdoor events fill the calendar, and long daylight hours make evening walks around the old town particularly atmospheric. Book accommodation early.
Autumn (September–October) is arguably the most characterful time to visit. The October Freimarkt — Germany's oldest folk festival, running for nearly a month — fills the city with fairground rides, traditional food stalls, and a genuine local atmosphere that few outsiders expect.
Winter (November–February) is cold (often near freezing) and grey, but Bremen's Christmas Market on the Market Square, held from late November to Christmas Eve, is consistently rated among Germany's top five. The Schnoor's lantern-lit lanes in December are genuinely magical. Outside the Christmas market period, sights are quieter and hotel rates drop significantly.