The Met Office have revealed when winter will officially start this year and has warned of a 'polar plunge'.
Despite seeing temperatures of above average throughout September and October, weather forecasters predict a wintery flurry will cast over Scotland in the coming days.
Over the last month, Edinburgh has seen temperatures rise up to 19 degrees and this week still hitting 17 degrees celsius, however winter is fast approaching with cold air coming down from the Arctic.
While today Edinburgh will feel warmer with highs of up to 17 degrees today (Tuesday October 19), thundery showers are forecasted for 8pm and then temperatures will drop tomorrow night right down to just five degrees.
The cold air is expected to bring some snow fall on higher grounds this week in a 'rare October phenomenon' around Scotland, as Ben Nevis has already seen some of the white stuff.
But as we haven't even got to Halloween yet, the start of winter can cause some debate with some rolling their eyes at Christmas decorations already.
As reported by the Daily Record, here is everything you need to know about winter 2021, when it officially begins, and how long is will last this year.
When does winter start in 2021?
Although the chilly air this week, winter actually starts depending on whether you follow the meteorological or astronomical calendar.
Winter begins on December 1 and lasts until the end of February - spring is March 1. The other date means winter finishes on March 20.
The Met Office use a meteorological definition of the seasons. By this calendar, the first day of winter is always 1 December; ending on 28 (or 29 during a Leap Year) February.
The Met Office states: "Meteorological seasons consist of splitting the seasons into four periods made up of three months each. These seasons are split to coincide with our Gregorian calendar, making it easier for meteorological observing and forecasting to compare seasonal and monthly statistics.
"The seasons are defined as spring (March, April, May), summer (June, July, August), autumn (September, October, November) and winter (December, January, February)."
According to the Met Office, the astronomical calendar "determines the seasons due to the 23.5 degree tilt of the Earth's rotational axis in relation to its orbit around the sun."
The winter equinox - the 24-hour period with the fewest daylight hours of the year - traditionally marks the start of winter.
Because the orbit of the Earth around the Sun is elliptical, the dates for solstices aren't fixed, though the winter solstice usually falls between December 20 and December 23.
Both Equinoxes and Solstices are related to the Earth's orbit around the Sun. However, the dates of the Equinox and Solstice aren't fixed due to the Earth's elliptical orbit of the Sun.
Winter start dates
| Winter 2021 | Tuesday, 21 December 2021 | Sunday, 20 March 2022 |
| Winter 2022 | Wednesday, 21 December 2022 | Monday, 20 March 2023 |
| Winter 2023 | Friday, 22 December 2023 | Wednesday, 20 March 2024 |
| Winter 2024 | Saturday, 21 December 2024 | Thursday, 20 March 2025 |
What is the Winter Solstice and when is it?
This year, the solstice is on Tuesday, December 21, roughly three weeks after what most people consider 'traditional'.
The winter solstice is the shortest day of the year and also the longest night.
This is because the Earth has turned on its axis so that the north pole tilts away from the sun and is at its furthest point from it for the entire year.
As a result of the Northern Hemisphere spending less time close to and facing the sun, the winter months are much colder and shorter. There are therefore fewer daylight hours and longer nights.
How long does winter last?
Despite different dates, according to both definitions, winter lasts around three months.
