During the transition season between winter and spring in Guangdong Province, many objects such as indoor floors, walls and glasses easily become damp and are often covered by a thin clay of condensed water. An analysis is made of such five cases of the special high humidity weather during February and March in 2012 in the aspects of physical processes and circulation patterns, air temperature and humidity characteristics, etc. The results indicates: after the termination of the influence of cold air, warm and wet air affects Guangdong when the dew point of outdoor air is higher than the indoor object temperature, and a high humidity weather event appears on the background of cold air making a sudden turn into warm air. During the transition season between winter and spring, when the high pressure ridge weakens rapidly, meanwhile there is obvious southerly air flow on 925 hPa, it is necessary to consider whether there appears a high humidity phenomenon during daily weather forecasting; the rapid rise of air temperature is the necessary condition for the high humidity phenomenon; the trend of future dew point should be selectively analyzed. The high humidity phenomenon normally disappears in two ways: cold ending and warm ending. Namely, Guangdong is affected by new cold air and the air temperature and dew point decrease dramatically, and the dew point is lower than the indoor object temperature; or air temperature rises up and lasts for a certain time period and the indoor object temperature is higher than the outdoor air dew point.