Ongoing East Asian monsoon conditions, with widespread cloud cover and scattered showers expected through mid-week, are the main driver keeping implied probabilities clustered tightly around 28–29°C for Seoul’s July 17 maximum. Latest Korea Meteorological Administration guidance and ensemble runs indicate modest daytime heating under variable insolation, with humidity near 80% limiting temperature spikes while steering patterns determine whether breaks in rain allow brief warming to 30–31°C or keep readings capped near 27°C. Historical July climatology places typical highs at 28–30°C, but short-term forecast spread in precipitation timing and thickness of marine layer clouds creates the narrow 4–5 percentage-point gaps between leading outcomes, with model updates over the next 48 hours the key variable for traders.