First Day of Autumn
Find the exact date and time of the first day of autumn (fall equinox) for any year with MiniWebtool’s First Day of Autumn tool, including a countdown timer, hemisphere selection and comprehensive seasonal information.
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About First Day of Autumn
Welcome to the First Day of Autumn Calculator, your comprehensive guide to finding the exact date and time of the autumn equinox for any year from 2000 to 2040. Whether you are planning seasonal activities, studying astronomy, or simply curious about when fall begins, this tool provides accurate equinox data for both the Northern and Southern Hemispheres.
At a Glance
First Day of Autumn shows the exact date and time of the autumn (fall) equinox for any year from 2000 to 2040. It supports the Northern and Southern Hemispheres and includes a countdown timer.
| Feature | What you get | Good for |
|---|---|---|
| Year range | Look up the autumn equinox for any year from 2000 to 2040, with a table of equinox dates. | Planning events or checking past and future years |
| Hemisphere choice | Northern Hemisphere autumn begins at the September equinox; Southern Hemisphere autumn begins at the March equinox. | Readers in either hemisphere |
| Countdown timer | A timer shows the days remaining until autumn begins. | Counting down to the start of the season |
| Two definitions | Compares astronomical autumn, which starts at the equinox, with meteorological autumn, September 1 to November 30 in the north and March 1 to May 31 in the south. | Knowing which start date a forecast or calendar uses |
| Seasonal background | Explains why the equinox date shifts from year to year and lists harvest festivals such as Mabon, Chuseok and the Mid-Autumn Festival. | Students and curious readers |
How to Use This Tool
- Select a year from 2000 to 2040 in the Select Year box.
- Select either Northern Hemisphere or Southern Hemisphere.
- Click Find the First Day of Autumn to see the date, the countdown, and the exact time.
The tool does not ask for your location or time zone. All times are shown in UTC (Coordinated Universal Time), the same worldwide reference clock. To convert to your local time, add or subtract your offset from UTC.
What is the First Day of Autumn?
The first day of autumn, also known as the autumn equinox or fall equinox, marks the astronomical beginning of the autumn season. On this day, the Sun crosses the celestial equator, resulting in approximately equal hours of daylight and darkness worldwide. This event occurs twice a year: in September for the Northern Hemisphere and in March for the Southern Hemisphere.
Astronomical vs Meteorological Autumn
🔭 Astronomical Autumn
Based on Earth's position relative to the Sun. Begins at the autumn equinox (September 22-23 for Northern Hemisphere, March 20-21 for Southern Hemisphere) and ends at the winter solstice.
🌡️ Meteorological Autumn
Based on temperature cycles and calendar months. In the Northern Hemisphere: September 1 - November 30. In the Southern Hemisphere: March 1 - May 31.
The Four Seasons Cycle
Earth's axial tilt of approximately 23.5 degrees creates the four seasons as our planet orbits the Sun:
Note: The months shown above are for the Northern Hemisphere. In the Southern Hemisphere, seasons are reversed.
Why Does the Autumn Equinox Date Change?
The autumn equinox does not fall on the exact same date every year due to several factors:
- Orbital period: Earth's tropical year is approximately 365.2422 days
- Leap years: The extra day in leap years helps correct the drift but causes date variations
- Precession: Earth's wobble on its axis causes gradual shifts over thousands of years
- Orbital eccentricity: Earth's slightly elliptical orbit affects timing
Autumn Equinox Traditions and Celebrations
Many cultures celebrate autumn harvest festivals:
- Mabon: A modern pagan celebration of the second harvest
- Mid-Autumn Festival: Chinese harvest festival held on the 15th day of the 8th lunar month
- Chuseok: Korean harvest festival held on the 15th day of the 8th lunar month
- Thanksgiving (harvest festivals): Celebrations of the harvest season in many countries
- Higan: Japanese Buddhist holiday for honoring ancestors
Frequently Asked Questions
When is the first day of autumn 2025?
The first day of autumn 2025 in the Northern Hemisphere falls on Monday, September 22, 2025, at 18:19 UTC. This is the autumn equinox, when day and night are approximately equal in length. In the Southern Hemisphere, autumn 2025 begins on March 20, 2025.
What is the difference between the autumn equinox and meteorological autumn?
The astronomical autumn begins at the autumn equinox (around September 22-23 in the Northern Hemisphere), determined by Earth's position relative to the Sun. Meteorological autumn, used by weather services, always begins on September 1 and ends on November 30 in the Northern Hemisphere, based on temperature cycles and calendar months.
Why does the first day of autumn change each year?
The autumn equinox date varies slightly each year because Earth's tropical year is approximately 365.2422 days. This fractional day causes the equinox to occur at different times, and leap years help correct this drift. The equinox can fall on September 21, 22, 23, or rarely 24.
Is autumn the same as fall?
Yes, autumn and fall refer to the same season. "Fall" is primarily used in American English, derived from "fall of the leaf." "Autumn" is more common in British English and comes from the Latin "autumnus." Both terms describe the season between summer and winter when leaves change color and temperatures cool.
When is autumn in the Southern Hemisphere?
In the Southern Hemisphere, autumn begins around March 20-21 (the March equinox) and lasts until the June solstice (around June 20-21). Countries like Australia, New Zealand, Argentina, and South Africa experience autumn during these months, which is spring in the Northern Hemisphere.
Additional Resources
Reference this content, page, or tool as:
"First Day of Autumn" at https://MiniWebtool.com/first-day-of-autumn/ from MiniWebtool, https://MiniWebtool.com/
by miniwebtool team. Updated: Feb 02, 2026
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