Current forecast models for Tokyo indicate overnight lows near 20–22 °C on June 28, driven by persistent cloud cover and scattered showers associated with the ongoing tsuyu rainy season. These conditions limit nighttime radiative cooling and keep minimum temperatures close to the late-June climatological average of roughly 21 °C. Recent short-range guidance shows a stable marine air mass with highs around 24–25 °C transitioning to the target date, reducing the likelihood of either strong cold advection or clear-sky radiative drops that could push readings below 20 °C. Market-implied odds favoring 21–22 °C therefore reflect the tight clustering of ensemble guidance around typical early-summer values rather than any anomalous event. Updated model runs and official Japan Meteorological Agency briefings over the next 48 hours remain the key catalysts that could shift probabilities if clearer skies or stronger winds develop.