Spring
In the UK Spring begins on March 21st each year, the day of the Spring Equinox is the day when the day and night are of equal length. After this day the daylight hours continue to increase until the Summer Solstice is reached.
Summer
In the UK, Summer begins on June 21st each year on the day of the Summer Solstice. This is the day when the length of daylight is at its longest. After this day the daylight hours decrease until the Winter Solstice is reached.
Autumn
In the UK Autum begins on September 21st, the day of the Autumnal Equinox. As with the Spring Equinox this is the day when day and night are of equal length. After this day the daylight hours continue decrease until the Winter Solstice is reached.
Winter
In the UK Winter begins on December 21st, the day of the Winter Solstice. This is the day when daylight is at its shortest. After this day the daylight hours increase until the Summer Solstice is reached.