Spring 2021 in United States

Spring Starts: Saturday, Mar 20 2:37 am PDT

Spring Ends: Sunday, Jun 20 8:32 pm PDT

Region: Washington/United States

The first day of spring (March equinox or vernal equinox) is when the sun shines directly on the celestial equator passing from south to north and the length of day and night are almost the same. This is referred to as astronomical spring or the March equinox or vernal equinox.

Astronomical spring starts at different times around the planet because of the different time zones as related to Coordinated Universal Time (UTC, same as Greenwich Mean Time based on the Royal Observatory in Greenwich, London [1]). For countries located west of UTC your spring will start earlier than countries located east of UTC.

Astronomical and Meteorological Spring

Astronomical Spring is determined by the changing positions of the earth relative to the sun giving us the solstices and equinoxes. Seasons are caused by the tilt of the earth on its axis by 23.5 degrees. The tilt of the earth does not change as it goes around the sun so in the Northern Hemisphere the earth is tilted toward the sun in June and away from the sun in December[2]. When the sun is over the equator you have the equinoxes and when the sun is over the Tropic of Cancer in the most northern position you have the Summer solstice and conversely when the sun is over the most southern position over the Tropic of Capricorn you have the Winter solstice. The March equinox occurs in the Northern Hemisphere between the dates of March 19 to 21 followed by the Summer solstice - June 20 to 22 and then the September equinox - September 21 to 23 and finally the Winter solstice - December 20 to 23. The United States, most of North America, Europe and many countries in the Northern Hemisphere use astronomical spring to determine when spring season officially starts and ends.

Meteorological Spring is determined by the annual temperature cycles and the Gregorian calendar. Meteorological spring starts March 1st in the Northern Hemisphere and lasts 3 months (March, April, and May) with Summer Season (June, July, and August) and Autumn Season (September, October, and November) and finally Winter Season (December, January, and February). Australia and New Zealand in the Southern Hemisphere use meteorological spring thus the months of September, October, and November to determine their spring season.

Many countries around the world depending on their latitude will use different methods to determine the start of spring. Some of these methods are dependent on the average daily/night temperatures, animal and plant behaviors, soil temperatures and their traditional calendar systems. More of these ecological methods to determine spring can be found on Wikipedia.org.

References:
1.”Greenwich Mean Time” - Wikipedia, wikipedia.org.
2.”Seasons and Earths axis” - National Weather Service, weather.gov.

Dates for Spring

Year	Spring Starts	Spring Ends
Spring 2023	Monday, March 20 2023	Wednesday, June 21 2023
Spring 2024	Tuesday, March 19 2024	Thursday, June 20 2024
Spring 2025	Thursday, March 20 2025	Friday, June 20 2025
Spring 2026	Friday, March 20 2026	Sunday, June 21 2026
Spring 2027	Saturday, March 20 2027	Monday, June 21 2027
Spring 2028	Monday, March 20 2028	Tuesday, June 20 2028