Abstract: Using the conventional and automatic observation data from the national and regional meteorological stations and the NECP (National Centers for Environmental Prediction) reanalysis data from 1976 to 2014,the characteristics of summer high temperature and circulation pattern in an extreme hot weather in 2014 over Zhuhai city were analyzed.The results show that the number of summer high-temperature days has increased since the late of the 1980s in Zhuhai city,and is higher in the eastern area than that in the western area.However,this situation has changed since 21st century.More high-temperature days appear in the western area.The extreme maximum temperature increases significantly.The increasing rate of extreme maximum temperature in the western area is higher than that in the eastern area.The characteristics of summer high temperature in Zhuhai city are related to the distribution of land and sea and the stage of urbanization.The high-temperature feature is unobvious in the eastern area where it is located near the coastal and in developed urbanization and is obvious in the western area where it is located in the inland and in developing urbanization.The circulation patterns over Zhuhai city can be divided into three types,i.e.the western Pacific subtropical high/ridge control,tropical cyclone control,and the common control by the subtropical high/ridge and a tropical cyclone.Under the last type of circulation pattern,the frequency of high-temperature days is the highest.In summer of 2014,the subtropical high ridge controlling over the Zhuhai city extends westwards,its strength is stronger,and its ridge line is located southwards.This circulation pattern finally results in the abnormally high temperature in Zhuhai city.

Key words: Summer, High temperature, Urbanization, Subtropical high, Circulation pattern