Recent forecasts from multiple models show a rain system arriving over Guangzhou around September 3–4, with moderate to heavy precipitation, extensive cloud cover, and lighter northerly winds expected to limit daytime solar heating and produce a daily maximum well below the early-September climatological average of 32–33°C. This pattern drives the market’s concentration around 27–29°C, as traders weigh the cooling effects of widespread rain and high humidity against any potential for partial clearing that could allow brief warming. Key variables include the exact timing and intensity of showers—afternoon downpours would cap the peak near 26–27°C, while lighter or earlier rain might permit 30°C or higher—plus model spread on boundary-layer moisture and steering flow. Historical analogs suggest such transient cool spells occur when monsoon or frontal influences briefly dominate, though forecast revisions within 48 hours remain the dominant source of uncertainty reflected in the broad price distribution.