Trader sentiment clusters around 29–31°C for Guangzhou’s June 17 high because ensemble forecasts show modest divergence in the strength and position of the western Pacific subtropical high and associated moisture transport from the South China Sea. Mid-June climatology favors afternoon maxima near 31°C, yet variable low-level convergence and potential for scattered convection can cap temperatures one to two degrees lower on any given day. Urban heat-island effects in the Pearl River Delta add a consistent but small positive bias to official readings. Fresh model guidance from the China Meteorological Administration and global ensembles over the next 48 hours will be the key catalyst that either tightens or shifts the current market-implied distribution.