Hong Kong Breaks 20 Weather and Temperature Records in 2025, City’s Sixth Hottest Year

All 12 months of 2025 saw temperatures higher than usual in Hong Kong, the city’s observatory has said.

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Hong Kong broke 20 weather and temperature records in 2025, the city’s sixth warmest year since record-keeping began in 1884.

All 12 months were warmer than usual, the Hong Kong Observatory (HKO) said last week. The annual mean temperature was 24.3C, 0.8C above the 1991-2020 average. The annual maximum temperature stood at 27.1C and the annual minimum temperature at 22.4C – one of the fifth and one of the sixth highest since 1884, respectively.

Hong Kong also saw a total of 20 record-breaking weather and temperature events. These included the highest absolute maximum temperature for June (35.6C), the highest total daily rainfall for August (398.9 mm), and the highest monthly mean temperature for October (25.6C).

Several record humidity measurements were also part of the list, including the lowest absolute minimum relative humidity for April (21%), the lowest seasonal mean relative humidity for spring (75%), and the absolute minimum relative humidity for November (16%).

Overall, 2025 was the year with the lowest mean relative humidity, on par with 1963. A study last year warned that climate change is making once-wet cities like Hong Kong exponentially drier, as it throws the water cycle “out of balance.”

Last year, the city’s hottest since since at least 1884, 35 temperature records were broken.

Hotter Days, Hotter Nights

“There were 53 very hot days, 54 hot nights in Hong Kong in 2025, both ranking third highest on record,” the Observatory also said.

For people living in places like Hong Kong, summer heat is nothing new. In the city, temperatures soar above 30C (86F) for most part of the year, which feel even higher when coupled with high humidity levels. Yet, heat-related illnesses here are on the rise.

A study conducted by researchers at the University of Hong Kong and published last year found that heatwaves in the city over the past decade, 18 in total, may have contributed to 1,677 excess deaths.

High nighttime temperatures are detrimental to human health, as they prevent the body from recovering from daytime heat. This not only disrupts sleep, which can negatively affect physical and mental health, cognitive function, and life expectancy, but it also increases the risk of illness and mortality.

A 2020 study by the Chinese University of Hong Kong (CUHK) found that five consecutive “hot nights”, defined as when temperatures rise above 28C (82F), would raise the risk of death by 6.66%.

With climate change, nights are not just getting warmer; they are also heating up faster than days in many parts of the world. According to a Climate Central analysis published last year, between 2014 and 2023, 2.4 billion people experienced an average of at least two additional weeks per year where nighttime temperatures exceeded 25C.

The impact of nighttime heat is uneven. Around 220,000 people live in 110,000 subdivided flats – tiny, crowded, often windowless spaces. Here, indoor temperatures at night can feel like 44C, according to a local NGO. 

More on the topic: ‘I Can’t Sleep’: Hong Kong’s Rising Nighttime Heat Exposes Inequalities

Record-Breaking Number of Typhoons

An unprecedented number of tropical cyclones, better known as typhoons in the Pacific, affected Hong Kong in 2025. “14 tropical cyclones necessitated the issuance of tropical cyclone warning signals, more than double of the long-term average of about six in a year, the highest annual number since 1946,” HKO said.

Among them were Typhoon Wipha in July and Super Typhoon Ragasa in September, both of which triggered the Hurricane Signal No. 10 in the city, the highest warning signal in Hong Kong. At the time it hit, Ragasa was the year’s strongest tropical cyclone globally, with highest winds of 270 km/h (165 mph). A subsequent study by ClimaMeter concluded that present-day atmospheric conditions resembling Ragasa are now wetter and warmer, favoring the kind of heavy rains, storm surges, and associated floods that devastated Luzon, Taiwan, Hong Kong, and Guangdong.

While tropical cyclones are a rather common weather phenomenon, there has been a significant increase in their intensity in recent decades that scientists attribute to warmer oceans. Ragasa and the 34 other tropical cyclones that occurred in the western North Pacific and the South China Sea in 2025 were fueled by higher-than-normal sea surface temperatures, HKO said.

Featured image: Kyle Lam/hongkongfp.com.

More on the topic: Warmer Climate Made Super Typhoon Ragasa 36% More Destructive in Southern China, Study Finds