Official Met Office and BBC forecasts point to a minimum near 18°C in London overnight into August 17, driven by a mild southwesterly airflow and limited radiative cooling under partly clear skies. Light winds and urban heat retention reduce the drop compared with rural areas, while above-average summer temperatures across southern England keep the air mass warmer than the long-term August average low of roughly 13–14°C. Ensemble model spreads introduce modest uncertainty between 17°C and 19°C depending on exact cloud timing and any weak frontal passage, explaining the tight market clustering around those two outcomes rather than cooler values. Updated guidance on the 17th will clarify whether any additional cooling materializes before resolution.