Shortest day of the year - when is it? Winter solstice UK explained plus winter 2025 start and end date

December is here, and that means Christmas is just around the corner. But, before what is the most magical day of the year for many comes the shortest day of the year.

With that also comes the longest night of the year. The event is known as the winter solstice. It always happens in late December, just days before Christmas. But, the exact date is changeable every year.

So, what exactly is the winter solstice, and when does it fall this year. Plus, when will winter 2025 officially end? Here’s everything you need to know.

When does winter begin?

There are actually two ways of calculating the first day of winter, depending on whether you follow the meteorological or definitions of the seasons.

But, whichever one you follow, both are happening in December. Meteorological winter comes first, and began in 2025 on Monday December 1, followed by astronomical winter which will begin on Sunday December 21.

What’s the difference between meteorological winter and astronomical winter?

These are the key differences between meteorological winter and astronomical winter, and how the date of each is determined.

Meteorological winter

The meteorological winter date is the easiest to work out.

It is based on the simple principle that the year is split into four seasons, and that each of these seasons are made up of three full months, as per the Gregorian calendar. This definition makes it easier to compare seasonal and monthly statistics, and means that every season starts on the same date every year.

This means that every year winter begins on December 1 and lasts until February 28, or on February 29 if it is a leap year, with spring then starting on March 1.

Astronomical winter

The astronomical season is less straightforward to work out as it can change every year. The astronomical calendar determines the seasons due to the 23.5 degrees of tilt of the Earth’s rotational axis in relation to its orbit around the sun.

Both equinoxes and solstices are related to the Earth’s orbit around the sun. There are two equinoxes a year; the spring equinox and the autumn equinox, and also two solstices a year; the summer solstice and the winter solstice.

The dates of the equinox and solstice aren’t fixed each year, however, due to the Earth’s elliptical orbit of the sun. This year, astronomical winter begins on Sunday December 21 and ends on Friday March 20.

What is the winter solstice?

The winter solstice, also called the hibernal solstice, occurs when either of Earth’s poles reaches its maximum tilt away from the sun. The winter solstice is the day with the shortest period of daylight and longest night of the year, when the sun is at its lowest daily maximum elevation in the sky.

The winter solstice occurs during the hemisphere’s winter. In the Northern Hemisphere, this is the December solstice, and usually takes place each year on 21 or 22 December. The term midwinter is also used synonymously with the winter solstice. Traditionally, in many temperate regions, such as the UK, the winter solstice is seen as the middle of winter.

Other names for the winter solstice are also the extreme of winter or the shortest day. The winter solstice 2025 is due to take place on Sunday December 21 at 3.03pm. The number of daylight hours on the shortest day will be around 7 or 8 hours, depending on where exactly in the UK you live. That’s 8 hours or 9 hours shorter than the summer solstice at the end of June, when daylight hours are at a maximum.

Daylight hours on this day will be around 8 hours in southern UK locations like London, but even less further north. For example, it will be more like 7 hours in Scotland.

When will winter end?

There are also two ways of calculating the last day of winter,

According to the metrological measure of the seasons, the last day of winter will be Saturday February 28 2026, with spring then starting on Sunday March 1 2026. But, the astronomical measure of the seasons states that the last day of winter will be on Friday March 20 2026, followed by the first day of spring on Saturday March 21 2026.