Met Office issue update on UK heatwave 'threshold' as temperatures to soar to 28C Temperatures could soar to 28C across parts of the UK during what the Met Office says will be "close" to a "heatwave threshold" The Met Office says some temperature records could be broken as the UK sees highs of 28C this week (Image: PA ) The Met Office has confirmed that temperatures will be "markedly higher" than what they should be for this time of year, reaching "close" to what the weather agency considers to be a heatwave. The UK is expected to see its hottest day of the year so far as it climbs to 24C or 25C on Monday (April 28), with the record likely to be broken in the following days until temperatures peak later this week. ‌ The Met Office says temperatures could peak at 28C – with a small chance of some areas seeing 29C – on Wednesday (April 30) or Thursday (May 1) this week. Article continues below Current forecasts also show widespread sunshine across the UK, with only the northern parts of Scotland expected to see some rain. Met Office meteorologist Craig Snell said: "We’re certainly on track to see the warmest spell of the year so far." Met Office temperature maps show highs of 27C in London at 4pm on Thursday (May 1) (Image: The Met Office ) ‌ He added: "There will be plenty of sunshine around, the very north of Scotland at times will see some spells of rain, especially at the beginning of the week, but it’s going to be limited to the far north of Scotland. "For a lot of the UK it’s going to be largely sunny." The Met Office said on X, formerly Twitter, on Sunday (April 27): "An early dose of summer is on its way. ‌ "With high pressure building this coming week, warm air will remain fixed across the UK." Content cannot be displayed without consent It added: "How high will the temperatures climb? Many of us can expect to pass the 20C threshold, with locally high twenties for some later in the week. ‌ "This is well above the late-April norm, which is usually 12-16C." What is the Met Office definition of a heatwave? Temperatures at the end of April are typically about 12C in the north and 16C in the south. Some areas could therefore be more than 10C higher than the average this week. Temperatures will be close to the Met Office "heatwave threshold" in some parts of the UK, according to Snell, but there is unlikely to be a heatwave widely. ‌ Temperatures could be "close" to a heatwave this week, the Met Office says (Image: PA ) The Met Office definition of a heatwave is three consecutive days of temperatures exceeding the "heatwave threshold" for that part of the country. For most of the UK, this is 25C, with slightly higher numbers for the South and East, and rising to 28C in London. The forecaster says the high temperatures could potentially break local temperature records, but records for April and May are unlikely to be broken. The temperature records currently stand at 29.4C for April and 32.8C for May. Article continues below On Friday (May 2), forecasts show that temperatures will start to drop towards the average for the time of year, with temperatures in the high teens in the South and mid teens in the North.