A blink-and-you’ll miss it ‘heatwave’ will gently warm the UK for about 24 hours before summer is once again blown away by the killjoy jet stream. Beleaguered Britons desperate for hot weather are on notice to be on standby in the south and east between Friday morning and Saturday night. Then, in keeping with the theme of 2024, the sun will retreat into hiding for the return of wind, rain and chilly grey skies. Met Office meteorologist Annie Shuttleworth said: “The heat is building across southern areas to end the week, but it is unlikely to last any more than three days as we then return to t…