Wynn D Woo It makes sense really because the first day of Spring is marked by the vernal equinox (Spring Equinox) which this year is March 20th, 2024 and the clocks go forward 11 days after.
Thus for us in Europe:
Spring is deemed to start at the Vernal Equinox (near 20 March)
Summer at the Summer Solstice (near 21 June)
Autumn at the Autumn Equinox (near 23 September)
Winter at the Winter Solstice (near 22 December).
https://www.rmg.co.uk/stories/topics/when-does-spring-start
In 2024 the clocks go forward on 31 March at 1am.
https://www.rmg.co.uk/stories/topics/when-do-clocks-go-forward