Recent Met Office guidance and ensemble forecasts highlight variable cloud cover and light winds over southern England as the key drivers behind the tight clustering around 12–13°C for London's overnight low on August 22. Clearer spells would enhance radiative cooling under high pressure, potentially pushing minima toward 11–12°C, while increased humidity or scattered showers from Atlantic fronts could limit cooling and favor 13–14°C. Historical August baselines show typical overnight lows near 13°C, but current model spread reflects uncertainty in exact timing of any frontal passage. Updated runs from the Met Office and ECMWF over the next 24–48 hours will likely refine these probabilities ahead of market resolution.