Brian Gaze from The Weather Outlook has told Express.co.uk freezing air from the Arctic is currently pushing southwards and hitting the northern half of the UK, increasing the rest of snow falling.
Millions of Britons could wake up to “widespread frost” on Monday with a chance temperatures could plunge to as low as -7C in the north.
The hugely unsettled weather looks likely to continue on Tuesday, as a clash of rain and colder air could again trigger a period of snow in the north.
Mr Gaze told Express.co.uk: “Much colder Arctic air pushes southwards during Sunday and in the northern half of the UK there is an increasing risk of snow showers. Over the Scottish mountains several cms of snow may accumulate.
“Monday is likely to begin with a widespread frost and in the north temperatures could be as low as -7C in places. The frost will be quite severe for the time of the year.
“As we head through Tuesday outbreaks of rain will be returning northeastwards; however, as they bump into the cold air over northern Britain they may be preceded by a period of snow.
“Accumulations are possible over high ground in northern England such as the Pennines and perhaps to lower levels in Scotland for a time, but by the end of the day any snow should be turning back to rain as it turns milder.”
He added: “Through the middle of next week temperatures rise and in sunny spells it should feel pleasant. With that said, it looks like a changeable picture with showers, longer spells of rain and strong winds all possible at times.
READ MORE: ‘I passed out drunk after a night out and woke up with rotting legs’
“Also, there is a chance of colder air returning southwards again later on, so all in all it’s a real mishmash of weather as spring struggles to get into gear.”
The latest UK weather maps from WXCHARTS show temperatures could plunge to as low as -4C in a region of northern Scotland and just a couple of degrees lower in surrounding areas.
This icy blue snap on the weather maps spreads southwards into northern England overnight with the mercury plummeting even lower north of the border to a chilly -5C.
The rest of the UK may struggle to see temperatures get above freezing, meaning millions of Britons could be waking up to a bitterly cold start to the week.
Arctic air could continue to linger over the UK until at least midday, with one weather map showing lows of -4C in Scotland, -2C in northern England and 0C in London and the Midlands.
This comes with the Met Office warning the UK could be facing bitterly cold weather over the coming hours that could trigger wintry showers and icy patches.
In its latest forecast for tonight, the agency said wintry showers in north and east Scotland will spread down coastal areas of eastern England. It will be mostly dry elsewhere the north in particular will be hit by a “widespread frost”.
Met Office forecaster Marco Petagna told Express.co.uk: “We’ve got some colder weather briefly moving in from the north across the UK over the next day or two, giving some wintry showers and icy patches in the north, with widespread frost.
“The weather then turns much milder, but unsettled from the southwest from Tuesday, with some heavy rain and possibly gales developing in places later this week.
“Heading into April the trend is for the weather to become less unsettled, especially in the north. Temperatures near average overall.”
