Hong Kong has sweltered through its hottest October since records began nearly a century and a half ago, figures from the Hong Kong Observatory have revealed

File photo: Kyle Lam/HKFP.

The mean daily maximum temperature over the month was 30.5 degrees Celsius, 2.4 degrees higher than normal. The mean temperature and mean daily minimum temperature, at 27.6 and 25.8 degrees respectively, were both 1.9 degrees above normal.

October also saw the latest-ever issuance of a Very Hot Weather Warning when temperatures in Yuen Long reached 36 degrees on October 21.

See also: Observatory warns Hongkongers to expect record-breaking heat in 2026 as UN chief raises alarm over climate crisis

This year’s super El Niño phenomenon – which sees sea surface temperatures in the central and eastern equatorial Pacific Ocean rise – has weakened the northeast monsoon, the seasonal wind pattern that typically blows cooler and drier air to Hong Kong from continental Asia.

Changing climate

Data from the Observatory shows that record after record is being broken in Hong Kong.

In the 2000s, the city recorded a yearly average of 13.4 “very hot days” – when the daily maximum temperature reaches 33 degrees or above. Since 2020, there have been more than 50 very hot days a year.

And the city is not just seeing more “very hot days” – it’s also experiencing them across a wider timeframe, beyond the traditional summer months.

Before the 2010s, very hot days were concentrated in June, July and August. In other months, they were rare. But over the past decade, very hot days have increasingly started as early as May and spilled into September and October.

See also: Hong Kong’s changing climate in 7 charts: from quadrupled ‘very hot days’ to record rainfall

Between 2021 and 2025, the city recorded a double-digit number of very hot days in September, compared to typical single-digit figures or even zero in previous years.

Last year, there were four very hot days in October. Before 2021, there were usually none.

Meanwhile, the past nine years were the warmest on record globally, according to the World Meteorological Organisation (WMO). Last year also saw global mean sea levels reach all-time highs owing to the melting of glaciers, ice sheets and continued ocean warming.