september

September is the ninth month of the Gregorian calendar. It has 30 days. The name comes from Latin septem, meaning seven, reflecting its position as the seventh month in the early Roman calendar before January and February were added to the front of the year.

In the Northern Hemisphere, September marks the transition from summer to autumn; in the Southern Hemisphere, it signifies the transition from winter to spring. The autumnal equinox occurs around September 22–23, when day and night are roughly equal in length.

Notable holidays and observances include Labor Day in the United States and Canada (the first Monday of September); Mexico’s Independence Day on September 16; and the International Day of Peace on September 21. The month also hosts cultural and religious events that vary by country and year.

Astronomically, the Sun moves from Virgo into Libra around September 22–23. The Harvest Moon—an informal name for the full Moon near the autumnal equinox—appears in many years. September is also associated with several traditional symbols: the birthstone sapphire, and birth flowers such as the aster and forget-me-not.