The grieving father of a teenager who died in a lake in Cheshire has warned young people about the dangers of open water swimming as Britain braces for its 'hottest ever day'.David-Junior Tita, 17, from Crewe, died at Pickmere Lake near Knutsford after entering the water with friends during record-breaking temperatures at the end of last month.He was reported missing before his body was found at around 5pm on Tuesday, May 26.The news came as a huge shock to his father, who had been watching the news on television and listening to a report about a teenager dying in water when police arrived at his door to deliver the devastating news. David Tita Snr was shocked as his son could not swim and told him he was going to the gym for the day.He paid tribute to his son, who he said was a 'hard-working' and 'popular' member of the community. The grieving father also urged young people to 'risk assess' their activities and consider the impact on their families if things go wrong. David-Junior, 17, died at Pickmere Lake in Cheshire during a record-breaking heatwave David Senior Tita (pictured with his son David Junior) was watching the news when police came to his door to tell him his son had diedThe father is warning other youngsters to take care as a 40C heatwave threatens to close hundreds of schools early, with people warned not to travel as a heat dome spreading across Europe reaches the country.Some schools have cancelled trips and are setting work for students to do at home, after the Met Office warned the heatwave is expected to bring 'severe and significant impacts', including widespread health risks for many.The rail operator urged passengers to only travel if 'absolutely necessary'.Temperatures in southern England could hit at 40C on both Wednesday and Thursday, followed by 33C on Friday.The UKHSA has upgraded its heat health alerts from amber to red for Wednesday and Thursday for much of England. Other amber heat health alerts will continue to be active from now until the end of Friday.Red alerts warn of 'increased risk to life across the whole population, with significant impacts on older people'; 'significantly increased demand on all health and social care services' and the 'heat affecting the ability of the workforce to deliver services'.David Snr urged any young people eager to cool off in water to opt for leisure centres, or open water areas with lifeguards, rather than taking risks with areas unsafe to swim.He also urged any youngsters who do not know how to swim to avoid taking the risk at all.