Recent forecast guidance from the Japan Meteorological Agency and ensemble models places Tokyo’s expected overnight minimum for May 17 near 17–18 °C, driving the tight clustering of market-implied probabilities around those levels. This range sits slightly above the long-term climatological baseline for mid-May, when average lows typically fall between 14 °C and 16 °C, reflecting a brief period of warmer advection ahead of an approaching frontal system. Key variables still under watch include the precise timing of any increased cloud cover or light winds that could suppress radiational cooling, alongside model spread in boundary-layer temperature forecasts. Resolution will hinge on the official JMA minimum reading at its Tokyo observation site, with new model runs and surface analyses expected within the next 24 hours likely to refine the final distribution.