Recent forecasts from the China Meteorological Administration and ensemble runs by ECMWF and GFS place Guangzhou’s May 18 maximum near 28–29 °C under patchy rain and lingering cloud cover associated with a weakening subtropical ridge. Mid-May pre-monsoon humidity above 80 % and southerly flow favor convective development that typically caps afternoon heating by 1–2 °C relative to clear-sky potential. Historical May daily highs average 29–30 °C, yet day-to-day variance remains high depending on the timing and intensity of morning showers. Traders therefore assign nearly equal weight to the 27 °C, 28 °C, and 29 °C bins, with resolution hinging on whether brief clearing allows temperatures to edge higher or persistent overcast keeps readings at or below 28 °C.