Traders see the tight spread between 6°C, 7°C, and 8°C outcomes because the latest Met Office guidance places London’s overnight minimum squarely in that window, with only modest differences in cloud cover and wind speed separating the exact value. Persistent stratocumulus and light northerly flow limit radiative cooling after sunset, keeping temperatures from dropping below the climatological May average of roughly 6–8°C recorded at Heathrow and St James’s Park. Model runs differ mainly on whether a brief clear spell develops before dawn, which could shave another degree, while stronger winds would hold readings near 8°C. With the day’s resolution imminent, new hourly observations and the final Met Office update will decide which single degree captures the most probability.