Heavy rainfall and extensive cloud cover expected over Guangzhou on June 17, driven by the East Asian monsoon and a strengthening low-pressure trough, represent the main factors moderating peak temperatures and shaping trader probabilities clustered around 29–31 °C. Numerical weather models show modest consensus on daytime maxima near 30 °C under persistent showers that limit solar heating and enhance evaporative cooling, while any delays in precipitation could allow brief breaks of insolation to push readings toward 32 °C. This uncertainty in timing and intensity, set against June’s climatological average high of approximately 31 °C, explains the relatively flat probability distribution across the leading outcomes. Updated model runs and official guidance from the Guangzhou Central Meteorological Observatory over the next 48 hours will provide the clearest signals for resolution.