In the capital, the mercury had already climbed to 18C by 5am, with the Met Office confirming that many areas across England — including Greater London — officially entered a heatwave on Friday. Yeovilton in Somerset and Crosby in Merseyside recorded the highest overnight temperatures in the country, both reaching 19.7C by 6am, while towns in Cumbria and Lancashire also reported overnight highs above 19C.