How many days until fall?

When does fall start?

Astronomical fall (autumn) in the Northern Hemisphere begins at the September equinox, usually on September 22 or 23, and ends at the December solstice. Meteorological fall runs from September 1 to November 30. Americans usually say "fall", from the falling leaves, while British English prefers "autumn". In the Southern Hemisphere, the September equinox marks the start of spring.

The autumnal equinox

At the equinox, the Sun crosses the celestial equator heading south, and day and night are roughly equal everywhere. After it, nights in the Northern Hemisphere grow longer than days until the winter solstice. The full moon nearest the equinox is called the Harvest Moon, because its bright light traditionally let farmers keep working into the evening.

Why leaves change color

Leaves are green because of chlorophyll, which plants use to make food from sunlight. As days shorten and temperatures cool, deciduous trees stop producing chlorophyll. The green fades, revealing yellow and orange pigments (carotenoids) that were there all along, while some trees, such as maples, produce red and purple pigments (anthocyanins). Sunny days and cool nights produce the most vivid displays. Peak color moves south through the season, from late September in northern New England to November in the southern states.

Fall traditions

• apple and pumpkin picking, hayrides, corn mazes and harvest festivals;
• football season, which starts around Labor Day;
• Halloween on October 31 and Thanksgiving in November;
• the Mid-Autumn Festival, celebrated across East Asia with mooncakes at the full moon of the eighth lunar month;
• Sukkot, the Jewish harvest festival, which follows Yom Kippur.

Getting ready for fall

Daylight saving time ends in the US in early November (see DST ends), so evenings get dark sooner. Fall is a good time to service heating systems, clean gutters and plan for the busy holiday season ahead.