When does Spring start this Year?
When is the first day of spring in 2021?
When spring officially starts, depends on whether you are more of an astrologer or a weather person.
This year’s spring can start either on March 1 or March 20 depending on how you look at things.
March 1 is set according to the meteorological calendar which splits the seasons into 4 clear periods, each season lasting 3 months on the Gregorian calendar, so May 31 will be the end of Spring. The Gregorian calendar was introduced to ensure seasonal statistics could be easily compared year on year.
According to the astronomical calendar however, spring arrives a full three weeks later on March 20 lasting until June 21. The date is different because the astronomical calendar uses seasonal data in relation to the degree axis of the Earth and the sun’s position of the equator. The seasons are set by solstices and equinoxes. Equinoxes being when the day and night are equal in length (12 hours exactly) and solstices being when the sun reaches either its year-high point in the sky at noon, or when it reaches its year low point. Equinoxes and solstices are not fixed as they are related to the earths tilted axis and orbit around the sun which is constantly changing.
The first day of spring for an astronomer therefore is one of the two yearly Equinoxes and this year it is March 20, when both our day and night will be exactly 12 hours.
Which first day of spring are you?