Hottest and Coldest Temperatures Ever in Philadelphia on September 21

On September 21 in Philadelphia, the weather varied from the hottest temperature ever recorded at 90.0°F in 1965 to the coldest temperature of 37.9°F in 1956. The average temperature for this date stands at 66.69°F, with an average high of 71.45°F and an average low of 61.94°F. In 1965, an interesting news item occurred where astronauts from the Gemini V spacecraft set a record for the longest manned spaceflight at the time, spending 8 days in orbit around the Earth.