It's the hottest day of the year so far, with temperatures of 26.6°C recorded in some parts of the UK.
Saturday was the warmest day of the year so far, but Ladbrokes are offering 2/1 for the mercury to reach 30°C or higher by the end of the weekend.
Jessica Bridge of Ladbrokes said: "It's getting hotter by the day and punters are convinced the sunshine's here to stay all summer."
Many Britons rushed to fire up the barbeque to make the most of the warm weather, while others flocked to the seaside or poured into Britain's parks and gardens.
Met Office forecaster Tom Crocker said forecasters were "fairly confident" Sunday would beat the top temperatures and "the majority of the country will see a dry day with plenty of sunshine".
However, pollution levels are expected to peak on Sunday, with high levels possible locally and widespread moderate air pollution.
The arrival of the warm weather also prompted several typically British complaints:
Those heading outdoors to enjoy the weather are also warned to be aware UV levels will be high.
Mr Crocker pointed out there is a "reasonable possibility" that people can get burnt if they are not protected
As the week progresses, temperatures are predicted to be mild, but will fall day by day.
Additional reporting by PA
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