Abstract: The relative humidity indexes in the past five decades are calculated based on the annual precipitation and temperature data from 34 meteorological stations from 1961 to 2011 in Chongqing. Moreover, Kriging spatial interpolation is conducted for the tendency and tendency coefficients of annual average temperature, rainfall and humidity index in each decade, and on this basis, the temporal and spatial variation characteristics of annual average temperature, precipitation and humidity index which reflect the wet and dry conditions in Chongqing are analyzed. Results show that 1) in the past five decades, the average annual temperature of Chongqing rose with fluctuations, with a rising rate of 0.09 ℃/(10 a), whereas in terms of spatial distribution, the trend rose from the southwest to the northeast yet with insignificant difference; 2) average annual precipitation showed a volatile downward trend with the tendency coefficient of 15 mm/(10 a), and in terms of spatial distribution the trend decreased from the southeast to the northwest; 3) the humidity index declined slightly overall, with the drought growing more intense from the southeast to the northwest, but in general, the difference is not obvious; 4) the coefficient of correlation between humidity index respectively with temperature and precipitation were -0.465 and 0.950.

Key words: humidity index, change of dry and wet stages, spatial interpolation, spatio-temporal characteristics, climate change, Chongqing