When Is the First Day of Fall in the USA? Key Facts About the Autumn Equinox

Fall has begun in the United States. The first day of fall in 2025 is Monday, September 22. The change of season was marked at 2:19 p.m. Eastern with the autumnal equinox. This moment happens when day and night are nearly equal in length across the globe.

The equinox is a natural marker used for centuries. It signals shorter days and cooler nights for the Northern Hemisphere. According to Reuters, the autumn season usually begins between September 21 and September 24 each year.

When Is the First Day of Fall Each Year?

The first day of fall is not always on the same date. Astronomical fall depends on the Earth’s tilt and orbit. In 2025, it fell on September 22. In other years, the date may be September 21, 23, or even 24.

Meteorologists use a different system. They define fall as starting on September 1 every year. This method is based on temperature patterns, not the solar cycle. It makes climate tracking easier and more consistent.

The astronomical equinox, however, is the official seasonal marker. On this day, sunlight is spread evenly across Earth. That is why daytime and nighttime hours are almost equal. From this point forward, nights in the Northern Hemisphere grow longer until the winter solstice in December.

What Does the Autumn Equinox Mean for the USA?

For many Americans, the first day of fall is cultural as well as scientific. It marks the start of harvest season, football games, and shorter evenings. Retailers and communities often launch fall events, festivals, and seasonal products at this time.

The change also reminds people of the upcoming clock adjustment. Daylight Saving Time ends on November 2, 2025. At 2 a.m., clocks will shift back one hour. This will bring earlier sunsets but give most people an extra hour of sleep.

The equinox also highlights Earth’s balance. While the Northern Hemisphere enters fall, the Southern Hemisphere begins spring. It is one of only two times a year when sunlight is distributed evenly across the planet. The other is the vernal equinox in March.

The first day of fall is more than just a date. It is a turning point in weather, daylight, and daily life. In 2025, fall officially began on September 22.

FYI (keeping you in the loop)-

Q1: When is the first day of fall in the USA in 2025?

The first day of fall in the USA is Monday, September 22, 2025. The autumnal equinox occurred at 2:19 p.m. Eastern.

Q2: What is the difference between meteorological and astronomical fall?

Meteorological fall begins on September 1. Astronomical fall begins with the equinox, usually between September 21 and 24.

Q3: When do clocks fall back in 2025?

Clocks fall back one hour on Sunday, November 2, 2025, at 2 a.m. local time. This marks the end of Daylight Saving Time.

Q4: Why is day and night equal on the equinox?

During the equinox, Earth’s axis is not tilted toward or away from the sun. This makes daylight and night hours nearly equal everywhere.

Q5: When does winter start in 2025?

Winter begins on December 21, 2025, in the Northern Hemisphere. That day is the winter solstice, the shortest day of the year.