Hottest and Coldest Temperatures Ever in Boston on September 21

On September 21st in Boston, temperatures have ranged from a scorching 88.0°F in 1965 to a chilly 41.0°F in 1956. The average temperature on this date is typically around 63.46°F, with an average high of 69.03°F and an average low of 57.89°F. In an interesting news story from 1965, Bostonians coped with the heatwave by flocking to the city's many public swimming pools to cool off, setting a record number of visitors for that year.