Boston's winters are typically cold and snowy, with temperatures often below freezing, ranging from -17°C in January to -8°C in December. Spring arrives slowly, with temperatures gradually warming up by March and April, which see highs around 22-25°C. Summer is warm but not hot, with July and August averaging around 21-23°C, while September brings a slight cooldown. Autumn is mild, with October and November experiencing temperature fluctuations between freezing and pleasant days.