**Forecasts from the Japan Meteorological Agency and other models indicate a highest temperature in Tokyo on June 15 most likely in the low 20s°C, with 21°C and 22°C as the closely matched leaders.** Mid-June marks the typical onset of the East Asian rainy season (tsuyu) across the Kanto region, bringing persistent cloud cover, scattered showers, and northeasterly flow that suppresses daytime heating. Current model consensus shows morning lows near 17–18°C and afternoon peaks limited by reduced insolation and evaporative cooling from rain, keeping maxima below seasonal normals of ~26°C. Slight differences between 21°C and 22°C hinge on the exact timing and intensity of any breaks in cloud cover or showers, as well as local urban heat island amplification in central Tokyo stations. Ensemble spreads remain narrow given stable large-scale patterns, but minor shifts in precipitation timing or wind speed could tip the recorded high. Historical June variability and the proximity to resolution amplify trader focus on the latest JMA and global model updates.