Seasonal Forecast for Summer June-August 2023 Assessment as of 30 May 2023 In the past month or so, the warming trend of the central and eastern equatorial Pacific continued. Sea surface temperatures of the region as a whole were above normal in April 2023. Based on the latest oceanic observations as well as forecasts by a number of climate models around the world, the central and eastern equatorial Pacific is expected to continue to warm for the next few months. An El Niño will develop by this autumn. Against the backdrop of climate warming, summer temperatures in Hong Kong exhibit a significant long-term increasing trend. The chance of normal to above-normal temperature is generally higher. Besides, the majority of climate models around the world forecast normal to above-normal temperature over southern China for summer 2023. Hence, the temperature of summer 2023 in Hong Kong is expected to be normal to above normal. Climate models around the world do not show a clear consensus of rainfall forecast for the coast of southern China for summer 2023. Taking into consideration objective guidance and statistical analyses of past performance of climate models and the development of El Niño and its impact on summer rainfall in Hong Kong, the chance of normal to below-normal rainfall in Hong Kong for summer 2023 is expected to be higher. Nevertheless, Hong Kong may still be affected by heavy rain. Members of the public are reminded to be prepared for the rain season. Note Climate prediction centres around the world generate seasonal forecasts, employing a variety of methods including dynamical models, statistical methods, expert judgment and combinations of them. Predictions from different centres do not always agree and large discrepancies can occur at times. The Observatory adopts an ensemble approach to formulate its seasonal forecast for Hong Kong, taking into consideration available products from major climate prediction centres and the Global-Regional Climate Model G-RCM operated in house. Thus, the resulting forecast issued by the Observatory may be different from the forecast given by G-RCM. The Observatory gratefully acknowledges the Tokyo Climate Center of the Japan Meteorological Agency and the National Centers for Environmental Prediction of National Oceanic and Atmospheric Administration, USA for providing dynamical prediction model forecast and hindcast data to support the formulation of seasonal forecast for Hong Kong. Seasonal Forecast for July-September 2023 will be available around 1st July 2023. Seasonal forecast charts provided by G-RCM and major climate centres G-RCM rainfall , temperature Beijing Climate Center Climate Prediction Center USA European Centre for Medium-Range Weather Forecasts The International Research Institute for Climate and Society USA Tokyo Climate Center UK Met Office For further information on this webpage, please contact Mr. W P Tse tel2926 3114, emailwptse