Temperatures of -7C (19.4F) were forecast in parts during the early hours of Monday with widespread lows of freezing.
Wintry weather will hold out until Wednesday when it will start to turn milder from the south, experts say.
Scotland and the north will struggle to catch up with snow forecast over the hills and even to lower ground.
Bitter northerly winds crept across Britain today triggering a sudden fall in temperatures.
Sunday was forecast to be the coldest of autumn so far with widespread harsh frosts likely tomorrow morning.
Met Office forecaster Marco Petagna said: “We could see -7C (19.4F) on Sunday night and through to Monday morning, this would be the lowest temperature of autumn so far bringing widespread frosts.
“Winds have started to come in from the Arctic and there is a risk of wintry showers in the north settling at 400 metres and falling to lower levels.
“Monday will be cold with temperatures in single figures across the country with similar temperatures on Tuesday.
Temperatures were forecast to hit -7C (19.4F) in rural areas last night (Sunday) with lows of freezing or below across the country.
Britons have been warned to wrap up from today with the mercury expected to remain in single figures.
The Met Office predicts highs of 12C (53.6F) or 13C (55.4F) in the south by Wednesday although Scotland and the north will struggle to get out of single figures.
Winter weather could set in earlier than usual this year taking hold at the end of this month, forecasters warn,
Some say this season could be the coldest for five years with odds already tumbling on a White Christmas.
John Hammond, forecaster for online service weathertrending, warned Christmas shoppers to brace for further cold weather this month.
Daytime temperatures could touch freezing by Black Friday – the busiest shopping day of the year which falls on November 24, he added.
He said: “Officially winter doesn’t begin until December but the meteorological models are increasingly showing it will arrive early.
“By Black Friday some areas of Britain could be seeing daytime temperatures of zero degrees – and this weekend’s night-time frosts will seem mild by comparison.”
Climate scientists have confirmed a La Nina ocean cooling is likely to become established in the eastern Pacific.
The phenomenon – which follows an El Nino warming pattern – is associated with colder winters in the UK.
The last La Nina hit at the end of 2010 at the same time a brutal big freeze brought swathes of the country to a standstill.
The Met Office’s professor Adam Scaife said: “Seasonal forecasts are now in agreement that a moderate La Nina is very likely to occur in the coming winter.”
Ladbrokes has slashed the odds for snow on Christmas Day from 5-6 to 4-5 with Aberdeen, Scotland, the favourite at 7-4.
Spokeswoman Jessica Bridge said: “The odds are falling as quick as the mercury and it looks like Snowvember is a sign of things to come over the festive period.”
Read more at Sunday Express