Fall dates shift each year because the calendar year and the astronomical seasons do not align perfectly. For 2018, the first day of fall is clearly defined by the Earth’s position relative to the Sun.
Below is a quick reference that captures the key astronomical and calendar details for the start of fall in 2018.
| Season | Hemisphere | Exact Start Date & Time (2018) | Corresponding Calendar Day |
|---|---|---|---|
| Fall (Autumnal Equinox) | Northern Hemisphere | September 22, 2018 at 14:54 UTC | Tuesday, September 22 |
| Fall (Autumnal Equinox) | Southern Hemisphere | March 20, 2018 at 16:15 UTC | Monday, March 20 |
| Meteorological Start | Northern Hemisphere | September 1, 2018 | Fixed three-month blocks |
| Time Standard | Both Hemispheres | Times referenced in UTC | Converts locally by timezone |
Understanding the Autumnal Equinox in 2018
The astronomical first day of fall is marked by the autumnal equinox, when daylight and night are nearly equal in length. In 2018, this moment occurs on September 22 in the Northern Hemisphere.
Because time zones shift the local clock time, the equinox may feel like it falls on different calendar days across the world. Yet the instant itself is universal, tied to the Sun’s position at 23:26 in Ecuador, or more precisely at 14:54 UTC.
Meteorological Fall versus Astronomical Fall
Weather and climate agencies often use a fixed calendar for seasons, which differs from the astronomical dates that change slightly each year.
Meteorological definition
Meteorological fall is strictly September 1 through November 30, aligning with temperature cycles and simplifying historical comparisons for records and averages.
Astronomical definition
Astronomical fall begins with the equinox and ends with the winter solstice, creating seasons of varying length based on Earth’s orbit.
Cultural and Regional Perspectives on Fall Start
Different cultures and regions may emphasize either the equinox or traditional harvest markers when signaling the transition to autumn. In many parts of the United States and Europe, the changing colors of leaves and cooler nights are felt as the practical start of fall, even if the calendar says summer lingers.
In the Southern Hemisphere, the same astronomical event marks the beginning of spring, demonstrating how the same celestial geometry supports opposite seasons across the globe.
Planning Around the Fall Equinox
Knowing the precise time of the equinox helps with scheduling seasonal events, agricultural planning, and photography trips aimed at capturing twilight shifts. Time zone conversion tools are essential for coordinating across regions.
Key Takeaways for 2018 Fall Start
- In the Northern Hemisphere, the first day of astronomical fall is September 22, 2018.
- The Southern Hemisphere experiences its spring beginning in March, not September.
- Meteorological fall is fixed to September 1 through November 30 for consistent climate analysis.
- Local time zones affect the calendar date when the equinox is observed day-to-day.
- Cultural perceptions of fall may align with weather changes rather than astronomical events.
FAQ
Reader questions
What date does astronomical fall begin in the Northern Hemisphere in 2018?
Astronomical fall begins on Tuesday, September 22, 2018, at 14:54 UTC, which corresponds to the autumnal equinox.
Does the first day of fall change if I am in a different time zone?
The equinox moment is based on UTC, so local clock time varies, but the calendar date can differ by region depending on the time zone offset at that moment.
Why do meteorologists use September 1 as the start of fall instead of the equinox?
Meteorologists use fixed dates to align with annual temperature cycles and to simplify climate recordkeeping, avoiding the variable length of astronomical seasons.
How can I plan my fall activities around the equinox timing?
By tracking the exact equinox time, you can schedule seasonal photography, outdoor events, and harvest celebrations to coincide with the shift in daylight and evening conditions.