The UK is bracing for an 'Arctic blast' that will bring significant drops in temperatures, particularly from Wednesday to Friday, with lows expected to reach around 1C in northern regions and around 7-8C in London. This cold spell follows a mild early autumn, with temperatures soaring to about 20C last week. The Met Office has issued yellow weather warnings due to potential thunderstorms and heavy rain, predicting unsettled weather patterns throughout the week. Despite the chilly forecast, warmer temperatures in the low 20s are anticipated by September 24. The cold snap will be characterized by blustery winds and frequent showers, particularly in the north, with drier conditions expected in the south. Overall, the transition from summer to autumn is evident as the UK prepares for this significant weather shift.