The meaning of September comes from ancient Rome: Septem is Latin and means seven. The old Roman calendar started in March, making September the seventh month. When the Roman senate changed the calendar in 153 BCE, the new year started in January, and September became the ninth month. In the Northern hemisphere, beginning of September leads to the beginning of meteorological autumn while it is the beginning of the meteorological spring in southern hemisphere. Some fun facts about September: The birthstone for September is the sapphire. The birth flower for September is the morning glory.