September 27 is a calendar date that falls in the early autumn of the Northern Hemisphere and early spring of the Southern Hemisphere. In the modern Gregorian calendar it is the 270th day of a common year and the 271st day in a leap year; after this date there are 95 days remaining until New Year's Eve. The ordinal position of the day shifts by one in leap years because of the added day in February, which affects day-of-year numbering across many record systems and software.

Characteristics

The date commonly lies under the zodiac sign Libra and is roughly five days after the autumnal equinox in the Northern Hemisphere when that equinox falls around September 22–23. Weather and daylight patterns on September 27 vary widely by latitude: many temperate regions are well into fall, while tropical areas may be in wet or dry seasons depending on local climate.

Observances and uses

  • World Tourism Day is observed on September 27, an international observance established by the United Nations World Tourism Organization to highlight tourism's social, cultural and economic value.
  • The date is often used for anniversaries, institutional celebrations, and locally observed holidays whose timing is fixed to the civil calendar rather than a lunar or movable system.
  • In databases and computing, September 27 is represented by its ordinal day number (270 or 271), which matters for day-count calculations such as age in days, fiscal period computations, and astronomical tables; for more on leap-year rules see leap years.

Because it is a fixed calendar date, September 27 recurs on the same sequence of weekdays only according to the seven- and 28-year cycling patterns determined by leap years and the structure of the Gregorian calendar. That makes it convenient for annual planning of events that do not follow religious or lunar calendars.

Historically, specific years' events that occurred on September 27 — such as political acts, battles, births or deaths — are recorded in chronologies and almanacs. When consulting historical sources, it is important to note whether dates are given according to the Julian calendar (used in many places in earlier centuries) or the modern Gregorian system, because the same calendar day can correspond to different dates in the other system.

In everyday use, people mark September 27 as part of late-September scheduling: academic terms, fiscal calendars that close in September, cultural festivals and the observance of international days. Its predictable placement near the season change makes it a natural reference point in seasonal reporting, travel planning and the scheduling of annual commemorations.