Trader sentiment for Tokyo's May 17 high clusters around 28–30°C because Japan Meteorological Agency models project afternoon heating to the upper 20s or low 30s under a persistent high-pressure ridge delivering clear skies, moderate southerly flow, and low dew points that favor strong insolation. Ensemble spreads of 1–2°C arise from uncertainties in the exact timing of peak solar heating, minor afternoon cloud buildup, or subtle wind shifts near the urban heat-island core, keeping the three leading outcomes nearly tied. Mid-May climatology at the Otemachi station averages 23–25°C, so these readings would mark an above-normal but not unprecedented warm episode; the next JMA update and afternoon observation cycle will refine the precise maximum used for resolution.