Persistent rain and thunderstorms forecast for June 17 are the main driver keeping Hong Kong’s daily maximum temperature expectations clustered around 28–30°C in the market, with 29°C leading. Cloud cover and high humidity from the active monsoon trough limit solar heating and evaporative cooling, suppressing peaks below the seasonal average of near 30–31°C despite the Hong Kong Observatory’s longer-term outlook for above-normal June temperatures overall. Recent heavy rainfall on June 15–16 has further cooled surface conditions and increased atmospheric moisture, reducing the likelihood of brief clear spells that could push readings higher. Forecasters note model spread in rainfall timing and intensity remains the key uncertainty, with any earlier clearing or lighter showers potentially allowing 30–31°C while sustained downpours would favor 28°C or below.