1. Based on the latest oceanic observations as well as forecasts by a number of climate models around the world, the sea surface temperatures over the central and eastern equatorial Pacific are expected to be near normal in the coming summer (June – August). Looking further ahead, some climate models suggest that the sea surface temperature in the region may decrease to the range of normal to below normal again later this year.
2. The current warm sea surface temperature anomaly pattern over the western Pacific is expected to persist for most of the time in 2025 (Figure 1). Generally speaking, the warm sea surface temperature anomaly pattern over the western Pacific will favour earlier onset and later cessation of typhoon season in Hong Kong as well as more tropical cyclones affecting the south China sea. This generally aligns with the predictions from the climate model predictions and objective guidance which also suggest the chance of having normal to above normal number of tropical cyclones coming within 500 kilometres of Hong Kong is higher.
3. Analysis of climate model predictions indicates that the tropical cyclone season in Hong Kong is expected to start in June or earlier this year, this may be related to the development of tropical cyclones along the monsoon trough over the south China sea and seas near the Philippines.
4. The annual rainfall in Hong Kong for this year is expected to be near normal. However, Hong Kong is still likely to be affected by rainstorms and localized heavy rain. Members of the public are reminded to be prepared for the rain and tropical cyclone seasons. As the climate continues to warm, the annual mean temperature in Hong Kong is expected to be above normal in 2025.

Figure 1 Sea surface temperature anomalies of 9 February – 8 March 2025 in degree Celsius.

1. The yearly numbers of tropical cyclones entering 500 km of and affecting Hong Kong are not necessarily the same. For example, even when a tropical cyclone comes within 500 km of Hong Kong, its weakening, change in movement or making landfall would not necessitate the issuance of warning signal. A tropical cyclone outside the 500 km range but bearing a large circulation or interacting with the northeast monsoon over southern China could affect Hong Kong and necessitate the issuance of warning signal. Since the long-term averages of the number of tropical cyclones entering 500 km of and affecting Hong Kong are roughly the same, the forecast of the former is, to some extent, indicative of the latter.
2. The Observatory will assess the situation around mid-year based on the latest available data, and provide update of the annual outlook as appropriate.