Current ensemble forecasts for Shanghai point to an overnight low near 26–27°C on August 13, driving the near-even split between those two outcomes in the market. Typical late-summer subtropical conditions—high humidity near 80 percent, light winds, and periods of cloud cover or light rain—limit nocturnal radiative cooling and keep minimum temperatures from falling much below recent climatological averages of 25–26°C. Small differences in forecast timing of showers or thickness of the marine layer explain the tight spread among 25–28°C probabilities, while lower outcomes would require clearer skies and stronger northerly flow not currently favored in guidance from agencies such as the China Meteorological Administration. Updated model runs overnight and early on the 12th will likely refine these ranges ahead of the observation window.