**Recent forecasts from the Japan Meteorological Agency and ensemble models show Tokyo's overnight low stabilizing near 21°C under mostly cloudy to overcast skies on June 14.** Persistent cloud cover limits nocturnal radiative cooling, anchoring minimum temperatures above the seasonal norm of roughly 19°C while suppressing stronger cold-air advection or high-pressure influences typical in early tsuyu conditions. Current observations and short-range guidance indicate no significant frontal passages or clear-sky episodes that would drop readings into the 19–20°C range, keeping the 21°C outcome dominant at 87.5% implied probability. Traders have updated positions based on the latest model consensus and real-time station data, with only modest volume on 20°C or 19°C reflecting residual uncertainty in exact timing of any late clearing. Urban heat retention in central Tokyo further supports the elevated floor. The next JMA update and any evening satellite trends on cloud trends will be the key near-term catalysts.