The temperature topped 20C on Thursday for the first time in the United Kingdom this year - and the unusually warm conditions are forecast to continue into the weekend.
A temperature of 20.1C was recorded at Otterbourne, Hampshire, a few days before the start of British Summer Time on Sunday.
Tuesday marked the official start of spring after a winter of largely mild conditions.
Forecasters have predicted that temperatures will reach 20C in London and the south east on Saturday and Sunday, with the rest of the country also seeing warm weather.
Nick Prebble, a meteorologist at MeteoGroup said: "This is unseasonably mild weather.
"Generally speaking, nine or 10 degrees should be the average maximum temperature for this time of year. We should enjoy it now while we can.
"On Saturday, London and the South East will be the warmest, but even up in Scotland it could hit 16 degrees.
"Up there they are not used to those temperatures at this time of year."
He added: "Sunday looks like it will be even sunnier.
"Temperatures in London should be 19 or possibly 20 degrees but the warmth will be more widespread across the country than Saturday."
A deckchair, thought to be largest in the world, was erected on Bournemouth beach in celebration of the Spring season.
But Dan Williams, a spokesman for the Met Office, cautioned that temperatures may cool in April.
He said: "We don't normally get a really long run of settled and dry weather, but we have now had a fair few days of above average temperatures.
"Moving into April, though, it looks like we will see more average conditions for this time of year, and rainfall will be closer to average."