When does Spring officially start?

27th February 2017 In Season

To most of us the month of March heralds the arrival of Spring but when does Spring officially start? With a name like Seasons, we thought it was the very least that we could do to get our facts straight!

Well the answer to the question depends very much on who you ask. There are actually two different methods used to determine the dates of the seasons and each method provides a different date for the start and indeed the end of spring.

Meteorological Seasons
Meteorological seasons are based on the weather and the calendar and this system means that spring officially starts on the 1st of March and ends on the 31st May. Whilst astronomical seasons depend on the Earth’s orbit of the sun, using this system spring starts on the 20th March and doesn’t end until 20th June.

If we were to ask Carol Kirkwood, she would tell us that The Met Office uses the meteorological seasons and that these are based on the annual temperature cycle and the state of the atmosphere. These seasons always co-ordinate with the calendar and they split the year into 4 three month seasons.

Spring – March, April, May
Summer – June, July, August
Autumn – September, October, November
Winter – December, January, February

Hence why by using this system spring starts on the 1st March and runs until 31st May.

Astronomical seasons
However if we were to ask Brian Cox, he would tell us that the astronomical seasons depend on the  position of Earth’s orbit in relation to the sun by taking into account the equinoxes. This is when the length of the day is exactly the same as the length of the night and solstices which are the longest and shortest days of the year.

The astronomical calendar determines the seasons by when the Earth’s rotational axis is at a 23.5 degree in relation to its orbit around the sun!

In the astronomical calendar, equinoxes mark the start of spring and autumn and solstices mark the start of summer and winter.

This year the spring equinox falls on the 20th March and the season lasts until the summer solstice on the 20th June.

All four of our seasons are due to the Earth rotating the sun and the way that the Earth rotates means that certain areas of the globe are tilted towards the sun while other parts are tilted away from it. This means that there is a difference in the amount of sunlight that reaches parts of the globe and causes these seasons.

We know that we have gone a little ‘off piste’ with this month’s article and had hoped to provide you with a definitive answer to the dates of our Great British seasons but as you will see it’s a little more complicated than one might have first thought. Nevertheless, we hope that you have enjoyed reading our very ‘seasonal’ blog and look forward to seeing you in the Spring!