Forecast models for Shanghai on June 1 converge on a maximum of 27–28°C, driven by the East Asian monsoon transition and early onset of plum rains that increase cloud cover and scattered showers, suppressing daytime heating. Ensemble guidance shows limited spread tied to boundary-layer moisture and rain timing, while early-June climatology typically holds highs in the mid-to-upper 20s Celsius under similar transitional patterns. This scientific consensus underpins the market-implied certainty around 28°C. Official observations from the China Meteorological Administration will confirm the outcome, though shifts in steering patterns or reduced precipitation could allow modest upward revisions.