Snow has been falling across some parts of the country just weeks after record-high temperatures at Easter.
It was just above freezing in Aboyne and Braemar in Aberdeenshire first thing on Friday morning, while there was frost in Shetland.
The chilly bank holiday weekend comes less than a fortnight after an Easter Monday that was the warmest on record for all four UK nations, with temperatures higher than 20C.
The temperature at Dalwhinnie in the Highlands was 0.1C at 2.30am on Friday and later in the day it was around 6C to 7C in north-east Scotland.
Temperatures were warmer in the west, reaching 11C at Port Ellen on Islay and 11C in Prestwick, Ayrshire, while it was milder in southern England and Wales.
Many people in Scotland took to social media to post footage and pictures of snow falling.
Temperatures could drop to as low as -2C on Saturday evening, with heavy showers and hail forecast across the east coast of England.
It will also be much colder than the same time last year, when the mercury hit 28.7C (83.6F) at Northolt, west London, making it the hottest early May bank holiday Monday and weekend since records began.
Temperatures will be slightly warmer on Sunday, with dry spells after a frosty evening.
London could enjoy reasonable weather going into Monday, with temperatures of 13C to be matched in the south and west of England.
Met Office forecaster Richard Miles said: “It will be colder, a lot colder, with showers in the north and the east of England.
“Saturday will be the worst day of the Bank Holiday weekend in terms of chilly showers and possible hail on the east coast, though Sunday and Monday will be a lot more settled.
“Sheltered, hilly areas in the north and Scotland could see colder and wintry weather in the evening from a northerly direction.
“The west should escape most of the colder weather, in Wales it could actually be quite nice, normal weather and the same in parts of Northern Ireland, as most places go to double figures during the day.”
The lowest temperature recorded on the early May bank holiday was -6.4C in Grantown-on-Spey in Scotland in 1981 and in Kinbrace in Scotland in 1988.
Asked about the chances of it being colder than that this weekend, Mr Miles said: “You’d be unlucky to see weather that cold, though some sheltered areas will feel very chilly.
“The coldest looks to be Aviemore in the Scottish Highlands, which could drop to -2C in the evening, with frosty weather in the hilly areas.”
Those travelling should expect disruption this weekend as parts of Britain’s railway will shut down for the second time in three weeks due to engineering work taking place.
No trains will run to or from London Euston between Saturday and Monday due to work in preparation for HS2 and there will be no trains between Bristol Parkway and Newport or between Shenfield and Southend Victoria.
In addition, Virgin Trains, which operates services on the west coast mainline, is urging passengers to “avoid travelling on these dates unless you absolutely have to”.
As a result, more road traffic is expected as 13 million leisure trips are to be taken by car between Friday and Sunday, according to RAC research, making it the busiest May Day bank holiday on the roads since 2016.