Recent Japan Meteorological Agency forecasts for Tokyo indicate minimum temperatures around 25–27°C on July 20, driven by a strong subtropical high-pressure system advecting warm, humid air northward and sustaining above-average summer conditions. This setup, combined with typical July climatology featuring overnight lows near 23–25°C, underpins the tight clustering of market-implied odds near 26–28°C at 35–37.5%. Model consensus shows limited spread, though variables such as nocturnal cloud cover, urban heat retention, and any late shifts in steering flow could nudge the exact minimum by 1–2°C. Updated JMA guidance and ensemble runs expected in the next 24–48 hours will provide the clearest near-term refinements for traders assessing these narrow probability bands.