September in Boston marks a transition from summer’s warmth to autumn’s crispness. Typical conditions involve gradually cooling temperatures, decreasing humidity, and an increasing likelihood of clear, sunny days. Average highs shift from the low 70s Fahrenheit (low 20s Celsius) at the start of the month to the mid-60s Fahrenheit (high teens Celsius) by its end. Overnight lows follow a similar trend, moving from the upper 50s Fahrenheit (mid-teens Celsius) to the lower 50s Fahrenheit (low teens Celsius). Rainfall remains moderate, similar to summer levels.
Understanding these seasonal shifts is crucial for planning various activities, from outdoor excursions and events to selecting appropriate attire. Historically, September has offered a pleasant balance between lingering summer warmth and the emerging beauty of autumn foliage, making it a popular time for tourism and local festivities. This period represents an optimal time for experiencing the city’s parks, walking trails, and historical sites before the onset of colder weather.