Forecast models from the Met Office and European Centre for Medium-Range Weather Forecasts show a stable high-pressure pattern over southern England, positioning maximum temperatures in London on September 30 most likely at 23°C or 24°C. These outcomes command the highest implied probabilities at 44% and 28.5%, consistent with ensemble consensus and recent surface observations indicating limited cloud cover and light winds. Key variables such as afternoon insolation and any late frontal approach could shift readings by 1–2°C. Updated model runs over the past 24 hours have narrowed uncertainty around this range, with resolution hinging on official Met Office maximum readings at standard stations.