**Trader sentiment for Seoul's June 13 minimum temperature clusters tightly around 16–18°C because official guidance and ensemble models currently converge on that narrow band amid typical early-summer variability.** With the market date only two days away, the leading outcomes (17°C at 29%, 16°C at 26%, 18°C at 23%) reflect modest differences in projected overnight radiative cooling rather than any major weather shift. Clear or partly cloudy skies allow greater heat loss from the surface, while higher humidity and light winds limit how far temperatures fall; conversely, increased cloud cover or a weak frontal passage can hold minima a degree or two higher. Current short-range forecasts from the Korea Meteorological Administration show morning lows in the mid-to-upper teens Celsius under generally stable conditions, consistent with June climatology where average overnight lows hover near 18–20°C before the full onset of the East Asian monsoon. Small revisions in model runs—particularly the timing of any marine layer or light precipitation—can easily move the expected minimum across the 16–18°C threshold, keeping probabilities closely matched and responsive to the next forecast updates.