UK temperatures have reached their highest point of the year, with 32.7C provisionally recorded at Heathrow, the Met Office said, beating the previous provisional high of 32.6C, recorded on Thursday. The heatwave in England and Wales is the first time since records began that temperatures have been higher than 30C for five days in a row in September, according to the Met Office. Previously the highest temperature of the year had been set on Thursday, with 32.6C recorded in Wisley, Surrey. While much of the UK has been sunny, forecasters have said there is an “increasing signal for a thundery breakdown for some later in the weekend”. The UK Health Security Agency has issued an amber heat health alert, meaning weather impacts are likely to be felt across the health service, with those aged above 65 or those with pre-existing respiratory or cardiovascular disease at greater risk. A yellow warning issued by the Met Office spans east Wales, Yorkshire, Lincolnshire, Manchester, Nottingham and Oxford, and will be in place from 2pm to 9pm. The same warning has been issued for Sunday covering Northern Ireland, northern parts of England and Wales as well as southern Scotland between 2pm and 11.59pm. The warning means some people could be in store for some flash flooding, lightning strikes, hail or strong winds, with possible interruptions to road access and public transport if such circumstances were to occur. The London mayor, Sadiq Khan, has issued a “high” air pollution alert for the capital for Saturday, the first since June, and urged Londoners to stop their engines idling and refrain from burning wood or garden waste. The UK is expected to return to cooler weather next week with a mix of sunshine, showers, and some windy conditions likely as temperatures go back towards the average for the time of year.