The Met Office has confirmed Saturday as the hottest day of the year, with 25.5C recorded in Gosport, Hampshire.
And the UK is set for record-breaking temperatures over the rest of the Easter weekend, forecasters have said.
Temperatures are expected to climb to 26C on Easter Sunday and 27C on Monday, though north-west Scotland could be clipped by outbursts of rain.
The record temperature for Easter Sunday in the UK is 25.3C reached in Solent, Hampshire in April 2011.
The Solent also lays claim to the hottest Easter Monday with 24C recorded, also in 2011.
Met Office forecaster Helen Roberts said the Solent's records were the "ones to keep an eye on and could be broken".
The UK's warmest Easter temperature was 29.4C, recorded at London's Camden Square on Holy Saturday in 1949.
Asda, Sainsbury's and Waitrose supermarkets said they expected soaring sales of sausages, burgers, ice lollies and ice cream.
Sainsbury's told the BBC it expected sales of rose wine to jump by 40% compared to last week, fake tan to climb by 300% and sun cream by 800%.
Argos customers have been preparing for the hot weather, with sales of one air conditioning unit up 367% week-on-week.
Asda is expecting high sales of Easter eggs and legs of lamb to be joined by a jump in sales of barbecue food - including a run on potato salad.
Meanwhile a spokesman for Waitrose said the supermarket was expecting sales of kebabs and steaks to rise by 150% week-on-week, and burgers by 170%.
This year, Easter will fall on its latest date since 2011, meaning that warm weather is more likely than in those years when it is in March.
Easter falls on the first Sunday after the first full moon on or after the vernal, or spring equinox. The earliest Easter Sunday can be is 22 March and the latest it can fall is 25 April.