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When do seasons start and end?

Ask your Irish friends: 'when do the seasons start' and the answer is ‘it’s complicated’!

While much of the world relies on the meteorological and astronomical calendars, Ireland follows the ancient Celtic calendar.

Seasons in the Celtic calendar are grouped into three full months:

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


The Celtic Calendar: A Tapestry of Tradition

The Celtic calendar, also known as the Gaelic calendar, is rooted in Ireland's ancient Druidic traditions. Each season is associated with specific agricultural events.

"This goes back millennia", said Críostoír Mac Cárthaigh from the National Folklore Collection at University College Dublin.

"I think it's very much tied to the agricultural year. For instance, Halloween was the traditional end of harvest - when all the crops would be harvested and the animals were brought in”.

"So, the first day of November marks the beginning of Winter or the dark period of the year".

The Irish months also point to the old calendar.

'Meán Fómhair' - or September - translates to the middle of harvest or the middle of Autumn. 'Márta' - or March - translates to the middle of spring.

Dr. Aoife Ní Fhearraigh, a prominent historian specializing in Celtic traditions, emphasizes the cultural significance of the Celtic calendar: "The Celtic calendar reflects the intimate relationship between the ancient Irish people and nature. It symbolizes the cyclical nature of life and the importance of honoring the Earth's rhythms".

fog covers the steps on the Cliffs of Moher, Co. Clare

Meteorological Calendar: A Practical Approach

The meteorological calendar is also grouped into three full months, but the seasons begin a month later:

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

Meteorologists in Ireland, like their counterparts worldwide, use the meteorological calendar to simplify the tracking of climate patterns. According to this calendar, Spring spans from March 1st to May 31st, Summer from June 1st to August 31st, Autumn from September 1st to November 30th, and Winter from December 1st to February 28th. 

Meteorological centers around the world collect weather and climate records, and this method makes it a more consistent way of calculating long-term averages and annual seasonal climate summaries.

"It probably makes sense only because it conveniently allows us to put three months into seasons for statistical purposes", said John Wylie from the UK Met Office.

John Smith, a senior meteorologist at the Irish Met Office, offers insights on the practicality of the meteorological calendar: "From a forecasting perspective, the meteorological calendar provides a clear framework for analyzing climate trends and predicting weather patterns. It allows us to communicate forecasts effectively to the public".

Lahinch beach

Astronomical Calendar: Guided by Celestial Events

The astronomical calendar aligns with Earth's position relative to the sun and stars. The astronomical seasons are determined by specific astronomical events: the spring equinox around March 20th, the summer solstice around June 21st, the autumnal equinox around September 23rd, and the winter solstice around December 21st. These events mark the points in Earth's orbit where the tilt of the planet's axis results in varying lengths of daylight and changing temperatures. Professor Sarah Johnson, an astronomer renowned for her work in celestial events, adds, "The astronomical calendar provides a universal understanding of Earth's position in space. It helps us comprehend the changing seasons from a cosmic perspective, emphasizing the interconnectedness of our planet with the wider universe."

a diagram explaining how the astronomical calendar works


In Ireland, the approach to understanding seasons is as diverse as the landscapes that define the country. While the Celtic calendar pays homage to ancient traditions and cultural heritage, the meteorological and astronomical calendars offer practical and scientific frameworks for analysis. As we embrace these diverse perspectives, we gain a deeper appreciation for the cyclical rhythms that shape our world.

Newgrange, Co. Meath

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