Extreme temperature days in Hong Kong

Extreme temperature days for the period from 1947 to 1998 in Hong Kong were investigated. Significant decreasing trends of both warm and cold days were discovered. Warm days were more variable than cold days. It is found that extreme days were less persistent in the last decade. In winter, cold days were related to the intensified Siberian anticyclone bringing a cold, polar air mass and Northeast monsoon to south China, while zonal flow would create more frequent warm days. In summer, apart from the influence of tropical cyclones to the east or southeast of Hong Kong, the effect of strong and persistent southerly flow was another prominent factor producing extreme temperature days.