Trader consensus on Polymarket reflects tight uncertainty in Japan Meteorological Agency (JMA) and global model forecasts for Tokyo's highest temperature on April 9, with implied probabilities clustered around 17–20°C at 21.5–23.5% each, driven by ensemble spreads in GFS and ECMWF runs showing daytime highs of 18–21°C amid variable cloud cover and weak frontal passages. Recent JMA two-week outlooks indicate near-to-slightly above-normal temperatures for early April (historical average ~18°C), influenced by persistent high-pressure ridging over the Sea of Japan, but differing cloud predictions and southerly wind speeds create the razor-thin differentiation—clearer skies favor 19–20°C, while patchy rain risks capping at 17–18°C. Watch JMA's daily updates through April 7 for refined guidance on boundary layer mixing and urban heat effects.