Recent Met Office and ECMWF ensemble forecasts converge on an overnight minimum of 17–19 °C for London on 18 August 2026, with 18 °C as the most probable single value under largely clear, light-wind conditions. This consensus has remained stable over the past 48 hours, supporting the market’s heavy weighting toward the 18 °C (34.5 %) and 19 °C (45.5 %) outcomes. Primary scientific drivers include a mild maritime air mass, limited cloud cover that permits moderate radiative cooling, and London’s urban heat-island effect, which typically elevates central-city minima by 1–3 °C relative to rural surroundings. No strong frontal systems or significant wind shifts are indicated that would produce larger deviations. Historical August climatology shows average lows near 13–14 °C, yet current model runs place this night several degrees warmer, narrowing the distribution and leaving tails below 17 °C or above 20 °C with low implied probability. Updated model guidance and any last-minute changes in cloud or wind forecasts remain the key near-term catalysts for price movement.