Hong Kong heat records spark debate over safety warning levels

Hong Kong has experienced record-breaking extreme heat, with temperatures reaching 36.9 degrees Celsius at the Observatory headquarters and 39.8 degrees Celsius in Sheung Shui. The Hong Kong Observatory (HKO) has released Wet-Bulb Globe Temperature (WBGT) data for the first time, revealing that on August 9, all 10 monitoring stations recorded indices above 31. According to Japanese standards, an index above 31 constitutes a maximum red danger level.

Discrepancies have emerged between the HKO's Wet-Bulb Globe Temperature and the current Hong Kong Heat Index (HKHI) used by the Labour Department to issue work heat warnings. The HKHI places significantly less weight on solar radiation (5%) compared to the international WBGT standard (20%). Consequently, while WBGT levels indicated extreme danger, the Labour Department issued only a yellow warning, citing low humidity and good wind speeds as mitigating factors.

Extreme heat in the city is exacerbated by the urban heat island effect and climate change. Vulnerable groups, including the elderly, pregnant women, and those with chronic illnesses, are at higher risk. The Home Affairs Department provides temporary heat shelters across all 18 districts during Very Hot Weather Warnings.