**Trader consensus overwhelmingly favors a 21°C minimum for Seoul on June 18, reflecting current official forecasts from the Korea Meteorological Administration (KMA) and aligned models showing overnight lows stabilizing near that level under mostly cloudy skies with light winds and minimal cooling.** Daytime highs are expected to reach 26–31°C amid typical early-summer humidity, consistent with recent observations and seasonal baselines where mid-June lows average 17–20°C but have trended slightly warmer this period due to persistent high-pressure patterns. The strong market-implied probability (93.5%) stems from tight model agreement on the morning low recorded between 3–9 AM KST, with limited variance in ensemble runs. Realistic challenges include unexpected nocturnal cloud cover or a brief rain event enhancing radiative cooling, though current guidance assigns low odds to deviations below 20°C before resolution.