Recent Met Office and ensemble model guidance points to an overnight minimum near 12–13°C in London on September 10, with light southwesterly flow, increasing cloud cover, and dew points around 10–11°C limiting radiational cooling. This keeps the lowest reading above the long-term average of 11.9°C while preventing a sharper drop that clearer, calmer conditions would allow. Traders assign the highest probabilities to 12°C and 13°C because small differences in timing of the minimum or boundary-layer mixing can shift the observed low by 1°C, and current model spreads cluster tightly in that range. Resolution hinges on the precise hourly observation at the designated station, with any late-evening shower or wind shift offering limited upside for lower outcomes.