When Does Autumn Begin? Fall Start Date

As summer winds down, many eagerly anticipate the arrival of autumn. Known for its vibrant foliage, cooler temperatures, and cozy atmosphere, autumn is a favorite season for many. But when exactly does this transition occur?

Defining the Start of Autumn

The beginning of autumn can be defined in two ways: astronomically and meteorologically. These definitions provide different perspectives on when the season officially starts.

Astronomical Autumn

Astronomical autumn is determined by the Earth's position relative to the sun. It begins with the autumnal equinox, which is the moment when the sun crosses the celestial equator, moving from the Northern Hemisphere to the Southern Hemisphere. During the equinox, both hemispheres receive roughly equal amounts of daylight and darkness.

In the Northern Hemisphere, the autumnal equinox typically occurs on September 22 or 23. This marks the official astronomical start of autumn.

Meteorological Autumn

Meteorological autumn, on the other hand, is based on annual temperature cycles and aligns more closely with our perception of seasonal weather changes. It is defined as the period from September 1 to November 30. This fixed date range helps in comparing seasonal statistics and making climate predictions.

Why Two Different Dates?

The discrepancy between the astronomical and meteorological definitions exists because the Earth's orbit is not perfectly aligned with the calendar. The meteorological definition offers a consistent and straightforward way to track seasonal changes for record-keeping and forecasting purposes.

What to Expect in Autumn

Regardless of the specific date, autumn brings a host of changes and characteristics that many look forward to:

• Falling Leaves: Deciduous trees display stunning hues of red, orange, and yellow as they prepare for winter.
• Cooler Temperatures: The scorching heat of summer gives way to milder, more comfortable temperatures.
• Harvest Season: Many fruits and vegetables reach their peak ripeness, leading to bountiful harvests.
• Festivals and Celebrations: Autumn is a time for numerous festivals, including Halloween and Thanksgiving.

Planning for Autumn

Knowing when autumn begins can help you plan accordingly. Whether you're organizing a fall-themed event, preparing your garden for the cooler months, or simply looking forward to pumpkin spice lattes, understanding the timing of the season is useful.

So, mark your calendars! Whether you prefer the astronomical start on September 22 or 23, or the meteorological start on September 1, autumn is a season full of beauty and opportunity.