Abstract: According to the daily average temperature, maximum temperature, minimum temperature, relative humidity and wind speed from 1961 to 2010 in Tianjin, the changes of cooling degree days (CDD) and heating degree days (HDD), climatic change features during winter heating period and summer air-condition period were analyzed by a statistic method. The relations of the regional climate change with the HDD, CDD and the number of comfortable days were discussed. The results show that the variation trends of the HDD and CDD are contrary. The HDD decreases and the CDD increases significantly, and variation amplitude of the HDD is larger than that of the CDD from 1961 to 2010, especially after 1980s. The extreme weather is significantly correlated with HDD and CDD. The number of low temperature days decrease during winter heating period, while the number of high temperature days increase significantly during summer air-condition period. The number of cold uncomfortable days reduces during winter heating period and that of hot uncomfortable days displays an increasing tendency during summer air-condition period.  These variations have significant correlations with the simultaneous mean temperature. At the same time, the uncomfortable weathers are in a randomly increasing trend. This suggests that the regional climate change has an important effect on winter heating period and summer air-condition period in Tianjin with the climate warming.

Key words: Climate change, Heating period, Air-condition period