**Persistent cloud cover and rainfall from an active tropical low-pressure system over the northern South China Sea are the main drivers keeping overnight lows in Guangzhou clustered around 26–28°C for August 23.** As of August 21–22, 2026, this disturbance (recently upgraded to tropical storm strength in the Beibu Wan region) combined with the southwest monsoon is delivering widespread showers and thunderstorms across Guangdong. The associated extensive cloud deck limits nighttime radiative cooling, supporting minimum temperatures several degrees above the long-term August 23 average of ~25.4°C. Multiple forecast models currently project overnight lows of 26–28°C under these conditions, with high humidity (often >85–90%) and light winds further moderating temperature drops. This setup aligns closely with the market’s leading implied probabilities on 27°C, 26°C, and 28°C. No significant cold-air intrusion or clearing skies are expected in the next 48 hours that would push minima notably lower, while the warm, moist airmass makes sub-25°C readings unlikely without an unexpected shift in steering patterns. Official updates from the China Meteorological Administration and numerical model runs over the coming day will be the key near-term catalysts for any adjustment in trader sentiment ahead of resolution.