**Persistent late-August heat driven by the North Pacific high-pressure system is keeping Busan unusually warm, with recent forecasts showing overnight lows clustered in the mid-to-upper 20s °C amid high humidity and scattered thunderstorm chances.** On August 25, 2026, models indicate continued southerly flow of moist subtropical air, limiting radiative cooling overnight and supporting minimum temperatures near 26–28 °C for August 27. Thunderstorm activity forecast for that day could enhance mixing or produce brief cooling, yet the same moisture often prevents sharp drops, which helps explain the tight clustering of market-implied probabilities around 26–28 °C. Historical August averages place typical lows near 23–24 °C, so the elevated baseline this season—several degrees above normal due to the strengthened anticyclone—shifts the distribution higher while leaving room for uncertainty if stronger convection develops. Traders are therefore balancing the likelihood of a persistently warm, humid night against the possibility of localized cooling from rain, producing the near-even odds across the 23 °C-or-below, 25–28 °C, and 33 °C-or-higher buckets. Updated model runs and official Korea Meteorological Administration guidance ahead of August 27 will be the key near-term catalysts.