Traders see 26°C and 27°C as the most probable outcomes for Tokyo’s June 13 high because official Japan Meteorological Agency guidance and ensemble models currently favor a mostly cloudy day with highs near the long-term June average of 26–27°C. The onset of the tsuyu rainy season is introducing increased moisture and cloud cover from the stationary front, which limits daytime heating and keeps maximum temperatures from climbing higher despite seasonal warming trends. Minor differences in forecast timing of cloud breaks or localized showers create the tight spread between these two bins, while lower probabilities for 25°C or 28°C reflect the narrower uncertainty range in current runs. Updated model guidance expected within the next 24–48 hours will likely refine the exact peak.