The Met Office says there were record breaking temperatures in all four of the UK nations which recorded their warmest Easter Monday.
In Cardiff the mercury reached 23.6C.
Another day of spring sunshine saw highs of 25C at Heathrow and Northolt, in London, as well as Wisley, in Surrey, beating the previous English record of 24C in the Solent in 2011.
Temperatures reached 24.2C at Kinlochewe in the Scottish Highlands and 21.4C in Armagh.
The highs beat the countries' previous Easter Monday records of 21.4C at Culzean Castle on Scotland's Ayrshire coast in 2014, 23.2C in Nantmor in north Wales in 1984, and 21.1C in Northern Ireland's County Fermanagh in 1984.