Introduction to Spring

Cue the warmer temperatures, rain showers and blooming flowers–spring is almost here!

Understanding the Basics of Spring

What You Need To Know

• Meteorological spring and astronomical spring have different meanings
• Astronomical spring usually begins on March 20 in the United States
• The calendar date and time for March’s equinox fluctuates
• The amount of time Earth takes to revolve around the sun plays a role in when a season begins

Meteorological Spring

Meteorological spring always begins on March 1 and runs through May 30. It’s a three-month season which makes it helpful for analyzing data and seasonal trends.

Astronomical Spring

You’re probably more familiar with the “first day of spring” that shows up on the calendar. It’s also known as astronomical spring, March equinox, spring equinox or the vernal equinox. So, does spring always begin on the same calendar date and at the same time?

Variation in Spring Dates

The beginning of spring varies year to year. Spring begins on March 19, 20 or 21. Why the variation in dates? Believe it or not, it has to do with the Earth’s revolution around the sun.

Earth’s Revolution and Leap Years

The Earth takes about 365.25 days to complete a revolution around the sun. A normal year has 365 days. That extra quarter of a day (about six hours) is part of the reason the vernal equinox fluctuates by about six hours every year.

Fun Fact

Fun fact: The extra quarter of a day is also why we have a leap year every four years.

Spring Dates Until 2048

Until 2048, the March equinox will happen on March 19 every leap year. In between the leap years, the March equinox will occur on March 20.

Time Zones and Spring Dates

What about March 21? Time zones outside of the United States have had a March 21 equinox this century. However, the U.S. mainland won’t have a vernal equinox on March 21 at all in the 21st century!

Upcoming Spring Season

Spring 2025 runs from March 20 until June 20. Summer begins on June 20, 2025. Enjoy this transitional season before the heat and humidity move in for an extended stay!

Conclusion

Our team of meteorologists dives deep into the science of weather and breaks down timely weather data and information. To view more weather and climate stories, check out our weather blogs section.

Frequently Asked Questions

Q: What is the difference between meteorological spring and astronomical spring?
A: Meteorological spring is a three-month season that begins on March 1, while astronomical spring begins on the day of the vernal equinox, which can fall on March 19, 20, or 21.
Q: Why does the start of spring vary from year to year?
A: The start of spring varies due to the Earth’s revolution around the sun, which takes approximately 365.25 days.
Q: Will the U.S. mainland ever have a vernal equinox on March 21?
A: No, the U.S. mainland will not have a vernal equinox on March 21 at all in the 21st century.