Basel, Switzerland, experiences a transition from summer to autumn during September. Typical conditions include mild daytime temperatures averaging around 18-22C (64-72F), with cooler nights dipping to 10-14C (50-57F). Rainfall is moderate, occurring on an average of 8-10 days throughout the month. Sunshine hours gradually decrease as autumn approaches, offering around 6 hours of sunlight per day. This period generally sees less humidity compared to the summer months.
This time of year offers pleasant weather suitable for a range of outdoor activities. The transition period allows visitors to enjoy the remaining warmth of summer while experiencing the vibrant colors of early autumn foliage. Historically, September has marked the beginning of the grape harvest season in the Basel region, a tradition that continues to be celebrated today. Favorable weather conditions during this month are vital for successful harvests and contribute to the region’s renowned wine production.