Hong Kong Heatwave: Highs of 35°C Before Midweek Thunderstorms

The Hong Kong Observatory has issued a very hot weather warning as temperatures reach up to 35 degrees Celsius (95 Fahrenheit) on August 16 and 17, 2026. This heatwave will persist through Monday before a low-pressure system triggers squally thunderstorms and unsettled weather across the city by midweek.

The current weather pattern creates a dangerous intersection of extreme heat and sudden atmospheric instability. The transition to thunderstorms midweek adds a secondary layer of risk, as sudden heavy rainfall can lead to localized flooding in low-lying urban districts.

Temperature Spikes and Observatory Warnings

The very hot weather warning took effect at 6:45 a.m. on Sunday, August 16. According to the Hong Kong Observatory, temperatures across the city have fluctuated between 28 and 33 degrees Celsius. The heat is not uniform; specific inland areas are experiencing more intense peaks. In Tai Po, the mercury hit 34.8 degrees Celsius by noon.

Weak winds are currently exacerbating the heat by preventing the dispersal of warm air, effectively trapping the humidity over the urban core.

The Midweek Shift to Low-Pressure Systems

The respite from the heat will not be a gradual cooling. The Observatory reports that a low-pressure system is moving toward the region, which will bring a sharp transition to unsettled weather by midweek. This system is expected to produce squally thunderstorms, which often bring high wind gusts and intense, short-duration rainfall.

When heavy rains hit sun-baked pavement, the risk of drainage overflow increases.

Long-term Urban Heat and Infrastructure Stress

The city’s geography—hemmed in by mountains and the sea—makes it particularly susceptible to stagnant air masses during the summer months.

However, the immediate reality for most residents is a reliance on mechanical cooling.

Comparative Weather Outlook: August 16–21

The transition over the coming days shows a stark contrast in atmospheric conditions: