Ensemble forecasts from the China Meteorological Administration and global models like ECMWF currently project a Guangzhou high near 28–29°C on May 18, shaped by mid-May pre-monsoon warmth tempered by patchy rain and increased cloud cover from a weakening subtropical ridge. Moisture influx from the South China Sea and variable timing of convective showers create the narrow spread across 27–30°C outcomes, as even modest differences in solar heating or afternoon clearing can shift the peak by 1–2°C. Historical mid-May averages hover around 29°C, but elevated humidity often caps extremes below seasonal norms. Updated model runs and official station observations will resolve the market by day's end.