Trader consensus on Polymarket tilts toward an 18°C high in Shanghai on March 29 at 31% implied probability, driven by the latest forecast model ensembles from the European Centre for Medium-Range Weather Forecasts (ECMWF) and Global Forecast System (GFS), which show peak afternoon temperatures clustering around 18–19°C under mild southerly flow and partial sunshine. Recent 24-hour updates reflect a tightening model spread after yesterday's observations of 16–17°C highs amid light cloud cover, with urban heat island effects in Shanghai potentially boosting the diurnal maximum by 1–2°C above rural readings. Differentiating factors include timing of convective showers—favoring 17°C if clouds thicken—or clearer skies pushing to 20°C, against March climatological averages of 13–15°C highs. Hourly updates from the China Meteorological Administration expected throughout the day will refine trader positioning amid this tight 17–20°C uncertainty.