Up to 10cm of snow could hit parts of London and the southeast this evening, with 15cm forecast for some parts of Essex.
Areas of Scotland, southwest England, the Midlands, northwest England and Wales have already had snow this weekend, causing travel disruptions.
Ellie Wilson, a meteorologist at the Met Office, said: “Today’s been a bit more snow than we were originally thinking.”
The Met Office has updated its yellow weather warning, forecasting a band of sleet and snow to hit the southeast, with possible snowfall of between 2cm and 5cm quite widely.
The warning is in place between 6pm tonight and 9am tomorrow.
Forecasters say some areas of the UK could have more snow tomorrow, with a small chance that rural communities could be cut off.
The cold snap is expected to stay through next week, with overnight frosts and daytime temperatures dipping below freezing.
Check the forecast in your area
Parts of Essex may get between 10cm and 15cm over higher ground, with the Sky News weather team predicting an impact on early traffic on Monday morning and that the yellow warning may be “escalated later”.
Temperatures will fall overnight to between -4C and -6C for many.
Over the snow fields of Scotland, it may fall as far as -15C.
Possibility rural communities cut off
Sky News weather presenter Jo Edwards said: “The weather is set to remain very cold over the next few days as the Arctic flow continues.
“However, yet colder air is likely to sink southward on Wednesday while winds pick up, introducing a more noticeable wind chill factor.”
She added: “Freezing fog in the southeast is likely to be an issue tonight and Monday night too, reducing visibility in places to less than 50 metres.
“Where fog forms, there’s also likely to be ice, with the moisture in the fog turning to ice instantly when in contact with subzero ground temperatures.
“The fog risk reduces through Tuesday and Wednesday as the breeze picks up. However, this will just make it feel even more bitter, introducing a wind chill factor to conditions that are already perishingly cold.”
The RAC and North West Motorway Police both issued warnings about driving in the wintry conditions as the latter responded to traffic accidents on several major roads.
The Met Office said the conditions could lead to more travel disruption, especially on Monday morning, and a small chance of some rural communities becoming cut off along with a possibility of power cuts and mobile phone coverage being affected.
What temperature should you keep your home at?
The UK Health Security Agency (UKHSA) sent out a level three cold weather alert covering England until Friday, extending the alert from Monday.
It advised people to look out for friends and family who are vulnerable in the cold and to ensure they have access to warm food and drinks.
People should maintain indoor temperatures of at least 18C (64.4F).
Dr Agostinho Sousa, consultant in public health medicine at UKHSA, said: “Cold weather can have serious consequences for health, and older people and those with heart or lung conditions can be particularly at risk.”
He added: “If you have a pre-existing medical condition, you should heat your home to a temperature that is comfortable for you.
“In rooms you mostly use such as the living room or bedroom, try to heat them to at least 18C if you can. Keep your bedroom windows closed at night. Wearing several layers of clothing will keep you warmer than one thicker layer.”
