Current numerical weather prediction models, including those from the Met Office, indicate an overnight low near 9 °C for London on May 18, with ensemble spreads placing the most likely range between 8 °C and 10 °C. This tight clustering of market-implied probabilities reflects limited divergence among short-range forecasts two days ahead, driven by expected light winds and variable cloud cover that modulate radiative cooling overnight. Clear intervals would allow temperatures to drop closer to 8 °C, while increased low-level cloud or a passing shower could hold readings nearer 10 °C. Historical May minima in the city average around 8–9 °C, providing a climatological baseline that traders weigh against the latest model guidance. Next updated runs from the European Centre for Medium-Range Weather Forecasts are expected to refine the precise minimum.