Winter in the UK is typically the coldest season with the shortest days often accompanied by unsettled weather conditions.
When is winter?
The meteorological calendar classifies winter as beginning in December and ending in February. In the astronomical calendar, winter starts on the winter solstice, which is around 22 December in the Northern Hemisphere.
The winter solstice is the shortest day of the year and occurs when the sun is furthest south from Earth's equator and the Earth's Northern Hemisphere is tilted away resulting in less solar heating. After the winter solstice, days start to get longer with more hours of daylight.
Winter is also recognised as a season by ecologists who define a hibernal season for this period of the year when many animals adopt behavioural and physical adaptations to cope with low temperatures including hibernation and migration.
What is the weather like in winter?
Winters in the UK are characterised by having unsettled and windy weather, this may be due to the incoming depressions and fronts moving across from the North Atlantic. This can mean those living in northern and western parts of the UK can see mild but stormy winters.
The average winter temperatures are largely based on your proximity to the sea because water loses heat more slowly than air, so the sea stays relatively warm over the winter. January is on average the coldest month in the UK and December on average is the month with the least sunshine. The strongest winds seen in the UK are most frequent in winter and can be associated with depressions.
You can see what the weather has been like in the UK in winters of the past on the Met Office's Climate summaries pages.