Which Months Are the Fall Season?
Fall, also known as autumn, is a beautiful season marked by falling leaves, cooler temperatures, and the harvest. But exactly which months constitute fall depends on your location and how you define the season. There isn't a universally agreed-upon start and end date, as it varies slightly depending on meteorological and astronomical definitions.
Let's break it down:
Meteorological Fall vs. Astronomical Fall
There are two primary ways to define the fall season:
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Meteorological Fall: This definition is used by meteorologists and weather services for its practicality. It divides the year into four equal three-month seasons based on the annual temperature cycle. This means meteorological fall encompasses September, October, and November in the Northern Hemisphere and March, April, and May in the Southern Hemisphere. This consistent, calendar-based approach is useful for tracking weather patterns and climate data.
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Astronomical Fall (or Autumnal Equinox): This definition is based on the Earth's position relative to the sun. Astronomical fall begins with the autumnal equinox, which occurs around September 22nd or 23rd in the Northern Hemisphere and March 20th or 21st in the Southern Hemisphere. It ends with the winter solstice, around December 21st or 22nd (Northern Hemisphere) and June 20th or 21st (Southern Hemisphere). This means the length of the astronomical fall varies slightly each year.
What are the Differences Between Meteorological and Astronomical Fall?
The main difference lies in the timing and duration. Meteorological fall is always three months long, providing a simple and consistent framework. Astronomical fall, however, depends on the precise timing of the equinox and solstice, meaning its length varies from year to year.
When does Fall officially start?
The answer depends on which definition you use:
- Meteorological Fall: September 1st
- Astronomical Fall: Around September 22nd or 23rd (Northern Hemisphere)
Which months are considered Fall in the Southern Hemisphere?
In the Southern Hemisphere, the seasons are reversed. Therefore:
- Meteorological Fall: March, April, and May
- Astronomical Fall: Around March 20th or 21st to June 20th or 21st.
Ultimately, while the precise dates vary slightly, September, October, and November are generally considered the months of fall in the Northern Hemisphere, and March, April, and May are generally considered the months of fall in the Southern Hemisphere. The best way to determine which definition is most relevant to you depends on the context—whether you're tracking weather patterns, observing astronomical events, or simply enjoying the seasonal changes.
