Extreme levels of snow, rain and sleet are forecast for the next few days in parts of the UK.
Heavy snow is expected to cover large parts of Wales, while small storms will hit parts of London and the south-east of England, the Meteorological Office said.
Yellow Warning for Snow covers large parts of northeastern England and Scotland until 11 a.m., and most parts of Cornwall and Devon are likely to receive showers until 8 p.m., raising the risk of flooding and traffic disruption.
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The Environment Agency had 69 flood warnings across the UK on Friday evening, meaning immediate action is required, and 231 warnings, i.e. flooding is possible.
Meteorological Office spokeswoman Nicola Maxi said it was raining as the weather moved from the southwest to the front.
“We’ve had continuous weather forecasts from Friday evening for most of Cornwall and Devon until tomorrow (Saturday),” he said.
“When this rain starts to move northwards it will already be accompanied by cold winds in the UK, causing snowfall across most of Wales, where it is likely to fall at very high altitudes of up to 20cm.
“Large areas of the UK will see some sort of snow over the weekend, with warnings for most of Scotland and the northeastern part of the UK.
“Even London and some parts of the Southeast should see a little fury, which is unlikely to settle.”
It comes after parts of Scotland were covered in snow up to 19cm in 24 hours on Thursday night, while 30mm of rain was reported in southwest England.
Most parts of the UK and Wales will experience snowfall and widespread snowfall between Monday and Wednesday, with warnings of road closures, power cuts and hazards due to snow.
The MS said the weekends would be very cold, with high temperatures reaching 6C (43F) and freezing in both mornings.
He added: “As we move next week, another front will move from the southwest with long-term snow and ice conditions to much of England, Wales and Scotland.
“It is expected to be up to 5 cm off the coast, reaching 15 cm in most parts of Scotland and Wales.”
He warned drivers to prepare with caution for “dangerous” icy conditions.