Forecast models from agencies including the Japan Meteorological Agency indicate a high-pressure ridge over eastern Japan that should support afternoon highs near 28–29°C in Tokyo on August 13, with ensemble spreads reflecting modest uncertainty from variable cloud cover, humidity, and sea-breeze timing. Urban heat-island amplification and light southerly flow add a few tenths of a degree, while any increase in low-level moisture or partial cloudiness could cap readings at 27°C. Historical mid-August climatology places typical maxima around 31°C, but recent Pacific sea-surface temperature patterns and model consensus shifts have narrowed the likely range, prompting traders to weigh the next model updates against these threshold sensitivities.