Recent forecasts from sources like the China Meteorological Administration and global models point to the onset of Shanghai’s Meiyu (plum rain) season as the dominant factor moderating temperatures on June 13, with extensive cloud cover, high humidity, and scattered showers limiting daytime solar heating and keeping maximums near the 26–29 °C range. Seasonal baselines for early June average around 27 °C, while current ensemble guidance shows modest spread tied to the precise timing and intensity of frontal rain bands. Trader-implied probabilities clustered around 26–28 °C reflect this genuine forecast uncertainty, as small shifts in precipitation timing or boundary-layer moisture can alter peak readings by 1–2 °C. Upcoming model runs and official updates over the next 48 hours will likely refine these contours before market resolution.