Traders' overwhelming consensus on a 21°C high temperature in Chengdu on March 21 reflects precise convergence in ensemble weather models from the China Meteorological Administration and ECMWF, forecasting afternoon peaks under partly cloudy conditions with light southerly winds and low humidity. Historical March data shows average highs of 18-20°C, aligning with this mild spring outlook amid stable La Niña influences suppressing extremes. Supporting evidence includes hourly projections from multiple services consistently capping at 21°C, with minimal model spread indicating high forecast confidence. Realistic challenges include a sudden northern cold surge or urban heat island variability at monitoring stations, potentially shifting readings to 20°C or 22°C, though current atmospheric patterns make such deviations unlikely.