Recent forecast guidance from the Japan Meteorological Agency shows a strengthening high-pressure ridge advecting warmer subtropical air over the Kanto region, with model consensus pointing to afternoon highs of 28–30 °C in Tokyo on May 18 under mostly clear skies and light southerly flow. This setup supports the market’s leading 55.5 % probability on 28 °C or higher, as reduced cloud cover and low dew points allow strong solar heating to push temperatures well above the mid-May climatological average of 23–25 °C. Minor model spread around the exact peak leaves the next most likely outcome at 27 °C with 23.5 % implied odds, while cooler scenarios remain unlikely barring an unexpected frontal passage.