A subzero start for Britain will be almost immediately thawed out with temperatures soaring to as high as 18C by the afternoon in a dramatic swing.
Met Office meteorologist Alex Deakin said some rural areas could drop to as low as -5C in the early hours before large parts of Britain move into the teens by 3pm.
London, for example will start teetering over freezing at 2C before reaching highs of around 15C.
The finer weather comes as Britons were warned yesterday they could be fined if caught outside their homes for non-essential purposes with the UK now on coronavirus lockdown.
But with are allowed to enjoy the sun in our gardens, which could be something of a blessing as the majority of children are off school for the foreseeable future.
The welcome upturn in British weather in just a matter of weeks since the cold snaps and heavy rain saw catastrophic flooding, we are set to match temperatures in the likes of Greece and Malta this week.
Parts of north-west Scotland, meanwhile, will remain "soggy" said Mr Deakin, with yellow weather warnings in place until Wednesday.
He described Tuesday beginning with a "chilly night under clear skies, [and] for some a touch of frost in places".
The south will see the lowest temperatures overnight from Monday with "towns getting close to freezing" while "rural areas through England and Wales [could see] -2, maybe even as low as -4 or -5 in some spots", he admitted.
But with temperatures quickly climbing as Tuesday unfolds, Mr Deakin said the persistent breeze in the north will make it "cooler than these temperatures would suggest" - including 15C in Glasgow.
"But for England and Wales, well we could easily with some sunshine get into the mid teens, 17, 18 is possible," he added.
The latest weather front, which could see 10 consecutive days of sunshine and highs matching the Mediterranean, is thanks to a 500 mile-wide 'Portuguese pulse' of warm air.
And with some reports suggesting temperatures could reach 21C in the near future, bookmakers have been slashing the odds on spring being the hottest ever.
From 6pm today until midday on Wednesday heavy persistent rain in north-west Scotland may lead to impacts from flooding, warns the Met Office which has issued weather warnings.
