Easter egg hunts could end in a melted chocolate mess as temperatures are expected to climb to a possible 18C (64.4F) in the south of England.
Hopes for al-fresco lunch on Easter Sunday may be fulfilled in some areas, with the weather feeling spring-like before the mercury drops by as much as 10C going into Easter Monday.
Chilly weather will arrive earlier in parts of northern Scotland where snow warnings are in place, while a shower of snow may also fall along some coastal areas of eastern England.
The public have been urged to respect the rules and only meet friends and family outdoors now that coronavirus restrictions have started to ease.
More than half of British households – 51% – had planned to swap a traditional Easter roast for a barbeque or picnic this year, a survey by Sainsbury’s found.
But a dinner indoors looks more likely in Fife, Strathclyde and the Highlands, which are due to see gale-force winds and snow showers as the country enters an “Arctic trough”.
By Easter Monday morning, there could be as much as 15cm of snow in higher areas.
The Met Office’s yellow warnings are in place from 6pm on Sunday until midnight on Monday.
Parts of the UK saw the mercury reach nearly 24C (75.2F) on Wednesday – a balmy high unlikely to be repeated on Easter Sunday.
Met Office forecaster Simon Partridge said the south of England can expect to see temperatures of 16C (60.8F) or 17C (62.6F) on Easter Sunday, with a high of 18C possible.
But this is expected to drop to 7C (44.6F) or 8C (46.4F) by Monday.
Talking about the pleasant weather on Easter Sunday, Mr Partridge joked: “You’ll have to make sure your eggs don’t melt if you’re hiding them in the garden because it will be quite warm.”