Britons basked, barbecued and burnt yesterday as the week-long heatwave reached a climax – at least for the happy majority.

Barely a month after Britain experienced the heaviest spring snowfall for nearly 20 years, temperatures yesterday climbed to 27.5C (81.5F), the hottest day of the year so far, more than 9C hotter than average for this time of year. The unseasonably pleasant weather did not reach everyone, however. Severe weather warnings were in place yesterday for Wales and parts of northwest England.

Great Malvern had the highest temperature of 27.5C. London was also one of the hottest parts of the country, and thousands descended on the city’s parks.

The sun was not kind to everyone yesterday as some visitors to Regent’s Park thought that tanning lotion was a precaution too far. Penny Taylor, 29, admitted that the marks left on her face by her sunglasses made her resemble a “pink panda”. Ms Taylor, a carer from Kensal Green in northwest London, said: “I shouldn’t have fallen asleep, but there was a lovely breeze so it didn’t feel too hot.”

Marion Russell, 31, who runs her own catering business, blamed a lunch-time drink for her lack of caution. “It doesn’t hurt now – my face just feels really hot – but I know I’m going to be in trouble tomorrow.”

The beach at Bournemouth was packed as sun-worshippers filled the resort’s seven miles of sand. Seafront car parks were full by mid-morning and beer gardens were not far behind.

Gwen Brookes, 24, set off early for Bournemouth from her home in Plymouth. “We wanted a day in the sun to try and get a bit of a tan because you never know if this is going to be the last nice day of the summer.”

In North Wales, the seafronts at Rhyl, Colwyn Bay and Llandudno were crowded, prompting hoteliers to hope that good weather combined with the credit crunch and well-publicised airport problems might lead to a bumper summer for British tourism.

The good weather there was in stark contrast to South Wales earlier in the weekend, when rain fell at what forecasters described as an “incredible rate”. Emergency teams were called to Chepstow, Cardiff and Swansea as storms hit on Friday night and in the early hours of Saturday.

Gwent Police said that a police station in Chepstow had been knee-deep in water, and Mid Wales Fire and Rescue Service received 44 calls from people in Swansea.

In Southsea, Hampshire, a young man was airlifted to hospital with serious injuries after falling 30ft from South Parade Pier. The pier is a popular location for “tomb-stoning” and police were last night trying to establish whether the 20-year-old jumped into the shallow water below or fell.

The contrasting meteorological fortunes of different parts of Britain reflect the dramatic shift in weather trends in the past month.

Five weeks ago, the country awoke to a blanket of snow and maximum temperatures of 6C (43F). By contrast, for the last week, with much of the near Continent enjoying prematurely summery conditions, increasingly warm weather has been blowing Britain’s way.

While holidaymakers in Spain would have been disappointed yesterday by “wet and cloudy” weather, said Andy Boddenham, a Met Office forecaster, much of Britain had been getting warmer each day. The bookmakers William Hill were offering odds of 25/1 that the May record will be broken. Meanwhile, Mr Boddenham had mixed news for those looking forward to topping up their tans in the week ahead. “We have probably seen around the highest temperatures for now,” he said.