Weather model consensus from agencies including the China Meteorological Administration and global ensembles indicates minimum temperatures in Shanghai on August 19 clustering around 26–27°C, matching the market’s leading implied probabilities. Late-summer conditions under the western Pacific subtropical high promote warm, humid air masses with modest nocturnal radiative cooling, while variations in cloud cover, humidity, and light precipitation potential drive the 1°C spread between leading outcomes. Urban heat island effects in the densely built city can further moderate overnight lows relative to surrounding rural areas. Historical August minima average near 26°C, underscoring the narrow uncertainty window. New high-resolution model runs over the next 48 hours will likely tighten the forecast ahead of market resolution.