Recent Japan Meteorological Agency model runs indicate Tokyo's overnight low on May 19 will likely settle near 19 °C under a stable high-pressure ridge and light southerly flow advecting warm Pacific air. This aligns with climatological mid-May baselines of 15–18 °C while reflecting the current above-normal temperature pattern across eastern Japan. Minor cooling from a weak cold front or northwest wind shift could push the minimum to 18 °C, whereas clearer skies and continued southerly advection favor 20 °C. Traders closely track the next 48-hour model updates, as small changes in wind direction or cloud cover will determine the exact threshold within the narrow 18–20 °C cluster that now dominates market-implied odds.