How Long Exactly Does Spring Last? Everything About the March Equinox in the United States

In just two days, on March 20, 2026, the United States and the Northern Hemisphere will experience a crucial astronomical event: the equinox marking the official start of spring. This moment is not just a calendar reference but a turning point that will determine how long this season lasts and what changes it will bring. Spring is much more than a date change; it is the period when natural cycles reawaken, temperatures begin their steady rise, and life on the planet undergoes one of its most visible transformations.

Spring 2026: 92 Days of Gradual Transformation

Spring will last approximately three months, totaling 92 days and 17 hours. This period will officially begin on Friday, March 20, and extend until June 20, when summer begins. During these nearly three months, nature undergoes noticeable changes: trees regain their foliage, plants and flowers bloom, temperatures gradually increase, and the photoperiod (day length) significantly lengthens while nights shorten.

The exact duration of spring is directly related to Earth’s orbital movement around the Sun. From the vernal equinox to the June solstice, Earth completes about a quarter of its orbit, defining the temporal boundaries of this crucial season.

What Time Will the Spring Equinox Occur?

According to The Old Farmer’s Almanac, the astronomical event marking the official start of spring in the Northern Hemisphere will occur on Friday, March 20, at 10:46 AM Eastern Standard Time (EST). At that precise moment, the Sun will cross the Celestial Equator, the imaginary projection of Earth’s equator onto the celestial vault.

This crossing of the Celestial Equator creates a special phenomenon: for a few hours, day and night will be nearly equal in length worldwide (hence the term “equinox,” meaning “equal nights”). From that moment, daylight hours will gradually increase over the next three months, providing more sunlight and stimulating changes in the biological cycles of plants and animals.

It is important to note that while the Northern Hemisphere celebrates the start of spring, the Southern Hemisphere simultaneously experiences the beginning of autumn. Both events occur at the same astronomical time, but their climatic consequences are opposite.

Why Do the Length and Start Date of Spring Vary Each Year?

A fascinating aspect of spring is that its start date is not entirely fixed. Although it generally begins on March 20, it can occur on March 19 or 21 depending on the year and time zone. This variability exists because there is a fundamental discrepancy between the Gregorian calendar and the actual astronomical year.

The astronomical year (the exact time Earth takes to complete one orbit around the Sun) lasts about 365 days and 6 hours, while the Gregorian calendar considers only 365 days. Those extra 6 hours accumulate year after year. To compensate for this difference, leap years are implemented, adding an extra day every four years, inserting February 29 into the calendar.

However, the leap year adjustment is not mathematically perfect, so the precise moment of the equinox shifts a few hours each year. This variation is why astronomical calendars must constantly recalculate the exact date of each equinox and solstice.

The Seasons of 2026: A Complete Calendar

To contextualize the duration of spring within the annual cycle, here is the full calendar of all seasons for 2026:

• Winter: Started December 21, 2025, and will end on March 20, 2026
• Spring: Starts March 20, 2026, and ends June 20, 2026
• Summer: Starts June 20, 2026, and ends September 22, 2026
• Autumn: Starts September 22, 2026, and ends December 21, 2026

Natural and Biological Changes During Spring

During these three months, spring brings significant transformations both astronomically and biologically. From an astronomical perspective, the apparent movement of the Sun northward causes days to lengthen consistently, providing more hours of sunlight in the Northern Hemisphere.

Climatically, temperatures begin their steady rise after the cold winter months. Plants bloom, trees regain their green foliage, and many animal species start their reproductive or migratory cycles toward higher latitudes. According to NASA data, spring involves a rebalancing of solar radiation cycles that sustain terrestrial ecosystems.

These natural changes also impact human daily life: outdoor recreational, sports, and social activities increase; people’s biological rhythms synchronize with the increasing light; and overall mood improves due to more sunlight exposure. The nearly three-month duration of spring allows a gradual, natural transition from winter cold to summer heat.

The Fundamental Role of Seasons in Life on Earth

The seasons are a direct consequence of Earth’s axial tilt and elliptical orbit around the Sun. They play an essential role in maintaining the planet’s climate balance, regulating the biological cycles of countless species, significantly influencing global agriculture, and determining animal migration patterns. Without these seasonal variations, life on Earth would be radically different, and many ecosystems simply could not exist.