Hundreds took to the streets to enjoy the wintery weather, with social media alight with images of snowmen and socially distanced snowball fights. The hashtag Narnia - in reference to the snow-covered fantasy world created by CS Lewis in the Chronicles of Narnia - was trending online.
Overnight, forecasters said temperatures may dip as low as -6C in the south east, while parts of the Midlands could see the mercury plunge to as low as -10C.
However, the Met Office said that, by Wednesday, temperatures across the south could have jumped back up to anywhere between 10C and 12C.
Monday was predicted to be bright and chilly with top temperatures of around 4C in the capital.
By Tuesday afternoon, heavy rain will have set in, with temperatures remaining cold, at about 2C.
But the mercury will steadily increase throughout the week, with warmer temperatures expected by Wednesday, according to the Met Office.
There will be rain overnight on Wednesday into Thursday, when London will potentially see highs of 12C.
For comparison, temperatures in Istanbul will struggle to hit highs of 6C this week, while in Marseille there will be highs of 12C.
But with the milder weather and rainfall comes a greater risk of flooding, with further problems possible in southern parts by the end of the week.
Met Office meteorologist Simon Partridge said: “It’s a bit of a rollercoaster from cold and wintry conditions to wet and windy ones.
“We are keeping an eye on rainfall totals because there are some areas that are very sensitive to rainfall and there is further possible flooding as we go through the second half of the week.”
The return of a warmer weather front will bring more anxiety to communities hit hard by Storm Christoph last week.
Many areas in northern, central England and Wales, particularly towns and villages along the River Severn in the West, endured flooding last week.
A recent investigation by Greenpeace’s investigative arm Unearthed and the Guardian found many flood defences across England could be in a state of disrepair following years of high rainfall.
The Environment Agency said, over the last year, repairs had been prioritised in areas at greatest risk.
A spokesman said: “We maintain approximately 78,000 flood assets across England, 95 per cent of which are in good condition and repairs prioritised where there is significant threat to lives and livelihoods.
“Our 2020 recovery programme inspected over 20,000 assets and, supported by a £120 million government investment, all of our assets are winter ready either through repairs or, where these have not been completed, robust contingency plans are in place.”