A heatwave driven by high pressure and clear skies is pushing minimum temperatures in London well above seasonal norms for mid-August, with Met Office guidance and ensemble models indicating overnight lows of 16–18°C on the 12th. This stems from sustained southerly flow and reduced radiative cooling under the current anticyclonic setup, following a week of rapidly rising daytime maxima that reached the upper 20s°C. Traders have concentrated probability on 17°C and 18°C outcomes because ensemble spreads remain narrow and climatological analogs for similar warm spells support only modest overnight drops. Key resolution hinges on the official daily minimum recorded by the Met Office station network, with final model runs and any last-minute cloud intrusions the main variables that could shift the exact threshold.