Spring (March-May)
Best overall. Temperatures climb from 8°C in March to 18°C in May, rain moderate. Wildflowers in Mullerthal peak late April. The Emaischen pottery market on Easter Monday in central Luxembourg draws locals. Hotels run 15-25% below summer rates outside Easter week. Whit Tuesday's Echternach Dancing Procession (May or June) is worth planning around.
Summer (June-August)
Peak season. Highs 24-26°C, occasional 32°C heat waves. All museums, cruises, and the Vianden chairlift run full schedules. Schueberfouer, Luxembourg's 700-year-old funfair at Glacis, runs late August to mid-September — book hotels well ahead. Downsides: hotels 30-40% pricier than spring, weekend queues at Bock Casemates, and the country partially empties in August as locals holiday.
Autumn (September-November)
Second-best season. September stays warm (20°C) and quiet after Schueberfouer ends. Moselle wine harvest festivals run through October — Wormeldange Grape Festival in mid-September is the biggest. November turns grey and 8°C; museum weather. Hotel rates drop to shoulder pricing.
Winter (December-February)
Christmas markets from late November through 24 December are the reason to come. The Winterlights markets spread across Place d’Armes, Place Guillaume II, and Place de la Constitution with $5 glühwein and $7 gromperekichelcher. January and February are cold (2-6°C), some castles closed, but hotels drop to $75-90 for city three-stars.
Good to know
Best month to visit Luxembourg?+
May or September. Warm enough for outdoor sights, dry enough for Mullerthal hiking, and cheaper than July-August.
Does it snow in Luxembourg?+
A few times each winter, rarely more than 5-10 cm and gone in days. Ardennes hills see more.
When are Christmas markets open?+
Late November through 24 December, daily 11:00-21:00. Some stalls extend to New Year but the atmosphere fades after Christmas Eve.
Worst time to visit?+
Mid-July to mid-August if you dislike crowds and heat, or January-February if you want everything open.