Current ensemble forecasts from the ECMWF, GFS, and China Meteorological Administration converge on a Guangzhou daily maximum of 27–28°C for May 18, driven by a weakening subtropical ridge that permits greater moisture influx and afternoon convective cloud build-up. This setup typically caps solar heating amid 70–80% relative humidity and light southerly winds, with model runs showing scattered showers limiting afternoon peaks near the historical May average of 29–30°C. The close 27–28°C split in trader odds reflects genuine uncertainty around whether brief clearing allows a 28°C reading or persistent overcast holds the high at 27°C, with resolution hinging on official station observations and any late-day model updates.