Official forecasts from the Met Office and supporting models indicate London’s overnight minimum on September 27 will likely reach 12–13 °C, driven by persistent cloud cover limiting radiative cooling and light to moderate southerly winds maintaining mild conditions. Hourly data show early-morning temperatures stabilizing near 13 °C before any slight further drop, consistent with climatological norms for late September and the absence of clear skies or stronger northerly flow that could produce lower readings. Trader consensus reflected in the 71 % implied probability for 13 °C and 29 % for 12 °C aligns with this narrow expected range, with resolution depending on the precise official minimum recorded during the overnight period.