Hottest and Coldest Temperatures Ever in Boston on May 21

On May 21st in Boston, the weather varied between extremes during different years. In 2009, the temperature reached a scorching high of 91.9°F—the hottest ever recorded for this date. In contrast, 1990 experienced a chilling low of 42.1°F, marking the coldest recorded temperature. On average, the temperature hovers around a comfortable 60.04°F on this day. Notably, during the same year as the coldest temperature, in 1990, a famous art heist occurred in Boston when two men disguised as police officers stole thirteen valuable artworks from the Isabella Stewart Gardner Museum—making it one of the largest art heists in history.