Severe drifting and blizzards are expected in parts of Wales, with the rest of the UK on standby for heavy snowfall throughout the day.
The battleground has been set all week, drawing cold air in from Europe to the east.
This week temperatures plummeted as low as -13.4 in Marham making it the coldest night of winter.
Weather fronts have been trying to push in from the west, with no success.
That all changes today.
An active weather front will finally cross the country, it will bring milder air in from the west and as this collides with the cold air it will immediately turn from rain to snow.
This band of snow will drive across most of the UK on Friday with a widespread covering across most of the UK and significant accumulations.
Strong to gale force winds will cause blizzard conditions and snow drifts, leading to travel disruption.
When will the snow arrive and how much will there be?
The band of snow will arrive into the south west from midnight.
By 6am it will be across much of Northern Ireland, Wales and south west England, with rain in Cornwall.
By midday it will be affecting all of Northern Ireland and Wales, plus into England as far as Lancashire-north Midlands and East Anglia (including London).
By the evening rush hour it will start clearing SW England and Wales, still snowing in Northern Ireland, the rest of Wales the rest of England and arrive in southern Scotland.
All day snow showers for eastern Scotland and northeast England will give 2-5cm of snow before the main band arrives.
The main snow band will set in across Scotland overnight and east from the southwest.
Many weather warnings are in force:
Yellow covers most of the country, away from NW Scotland and Cornwall here 2-5cm of snow is forecast with up to 10cm on hills.
Amber for western areas 5-10cm of snow is forecast with up to 15cm on hills.
A rare Red, the highest level of warning only issued a few times a year for SE Wales, 10cm of snow is forecast widely with up to 20-30cm on hills.
Adding in the strong winds the snow will blow around causing drifts and for some blizzard conditions, especially across Wales.
A strong southeasterly wind will develop and the areas for snow tomorrow will be different from today.
Northern Ireland, Wales and northern England will see snow, the heaviest in the east, exposed to the winds.
Expect 2-5cm of snow with 10cm on hills.
Further south it will be a quieter day with bright spells and only a few wintry flurries.
A cold day with snow turning to ice.
Sub zero temperatures mean an icy start.
Snow will still be lying across most of the UK.
Light winds mean it will also be a foggy start.
Fog will lift into low cloud during the morning and break through the day to give some sunny spells.
A much quieter day for all, largely dry, but southeast England and East Anglia can expect further snow.
Will we have more snow next week?
On Monday another weather front is set to arrive from the west and battle across the UK.
This brings another spell of fresh snow, and although this front will be less active than Friday’s, eastern Scotland and northeast England are in the firing line for some of the heaviest falls.
However, any snow will be unwelcome news.
Cold air stays with us well into next week with further spells of snow.
Overnight temperatures plummeting below freezing will cause icy conditions to develop as melted slushy snow refreezes.