The Met Office forecasts that temperatures in the UK could reach 26C this week, marking the potential for the hottest day of the year so far. This follows a record of 26.5C set on April 8 in Kew Gardens, London. On Thursday, southern areas can expect highs of 23C, while northern regions may reach 21C. The following day, temperatures are predicted to soar to 26C in the south and 23C in the north. A total of 53 counties across England and Wales are likely to experience temperatures of 20C or higher. However, despite the heat, this warm spell is not expected to qualify as an official heatwave, which requires temperatures to exceed the threshold for three consecutive days. The threshold varies from 25C to 28C depending on the region. While some showers may develop on Friday, the overall forecast indicates a warm and sunny weekend ahead.