The UK is experiencing a blast of cold Arctic air, leading to significant drops in temperatures across the country, with lows reaching -2C in the Highlands and around 6C in London. Snowfall has been reported on Scottish mountains, and many areas are facing daytime temperatures 4-7C below average. The Met Office warns that Friday morning will be particularly cold, with the potential for frost and snow flurries in some regions. However, warmer weather is expected over the weekend, with temperatures in London projected to rise to 19C and 22C by Sunday. Overall, while the cold spell is notable, it is not anticipated to last long, transitioning to milder conditions next week.