**Current numerical weather prediction models from sources like ECMWF and regional forecasts converge on a minimum temperature of 25–27°C for Guangzhou on September 26, 2026, under partly cloudy to mostly clear skies with light winds and moderate humidity around 50–60%.** This places the expected overnight low firmly in the mid-20s range, above the long-term September average minimum of ~23°C but well short of extremes. The near-even split between the 20°C-or-below (50%) and 30°C-or-higher (49%) outcomes reflects trader focus on the tails of forecast uncertainty: subtle differences in nocturnal cloud cover, radiative cooling rates under high humidity typical of the South China Sea monsoon transition, and urban heat-island effects in Guangzhou can shift the exact minimum by a couple of degrees. A stronger high-pressure ridge or clearer skies could allow slightly more cooling toward the lower 20s, while any increase in low-level moisture or light showers would suppress the drop and keep readings closer to 27–28°C. With resolution imminent, updates from official monitoring and short-range model runs over the next 48 hours will determine whether the minimum edges into one outcome or the other.