Rainfall New Cateriogies

“Severe Rainstorm” and “Exceptionally Severe Rainstorm” – extreme rainfall events in Hong Kong

Wong Ka-hing and Fan Man-hei

From 7 to 8 September 2023, extreme rainfall occurred in Hong Kong. The rainfall intensity during that rain episode far exceeded the public’s general understanding about rainstorms. To address the issue, starting from the rainy season of 2024, the Hong Kong Observatory has strengthened the dissemination of information about rainstorms and introduced two new terms – “Severe Rainstorm” (SvR) and “Exceptionally Severe Rainstorm” (ESR), which refer to rainfall intensity exceeding 100 mm and 140 mm in an hour, respectively. When the rainfall intensity reaches the SvR or ESR levels, the Observatory will alert the public through Special Weather Tips, advising them to pay attention to the exceptional weather and take preventive measures.

To learn more about extreme rainfall events in Hong Kong, please refer to this article in Educational Resources.

Flood in Wong Tai Sin (along Long Cheung Road) on 8 September 2023 (source: CRHK News).