Latest Japan Meteorological Agency (JMA) forecasts and ensemble model runs from global systems like ECMWF project a nocturnal minimum temperature of 12°C at Tokyo's Haneda Airport station—the market's official resolution site—under persistent cloud cover and light southerly winds that limit radiative cooling overnight. This tight convergence, bolstered by early morning observations already bottoming near 12°C amid scattered showers, underpins the 99.9% market-implied probability for 12°C, aligning with early May climatological averages of 13–15°C where sub-10°C lows are rare historical outliers. Realistic challenges include unexpected sky clearance before dawn enabling faster cooling to 11°C or below, or a late-shift in the weak frontal boundary introducing colder air, though current soundings and trends render these low-probability scenarios. Final Wunderground data finalizes resolution post-midnight.