Thunderstorms are forecast for much of the UK this weekend before the arrival of autumn weather, the Met Office has said. Some areas, particularly in the south, could get a final dose of summer heat, however, as temperatures remain high. National severe weather warnings are possible as humid air moves northwards, raising the risk of thunderstorms, the Met Office said. On Saturday, it would be cloudy in the north, while southern areas would get a dry start, although some showers and thunder were possible in the south and west. But as the day progressed it should be dry across the country. Night-time humidity was expected in the south, but in parts of rural Scotland, clear skies could result in frosts and temperatures dropping below zero. The Met Office meteorologist Ellie Glaisyer said: “It should be dry for most places, but it will be sunniest in the south-east and in the north of Scotland. “Temperatures of 27C are possible in the south-east, but in the north it will feel cooler, with temperatures staying in the mid-teens.” The mild and humid night in the south could make for “uncomfortable sleeping”, she said. “But in rural Scotland there will be less cloud cover – we could see frosts with temperatures dropping to minus 1C overnight.” She said widespread thunderstorms were forecast for Sunday “but it will start to get drier as the day goes on”. Temperatures in the south could reach 24C while in Scotland they would remain in the mid-teens. Unsettled weather on Monday and into next week would cause temperatures to return to the average for the time of year, and it would “start to feel fresher, and much more autumnal”.