The monthly dryness/wetness conditions were calculated by applying the Standardized Precipitation index (SPI) at the 6 month scale based on the daily precipitation records of 25 meteorological stations in Guangdong Province from 1960 to 2011. The methods including MannKendall trend test

Rotated Empirical Orthogonal Function (REOF) and wavelet analysis were employed to detect the spatial and temporal patterns of dryness/wetness conditions over Guangdong Province. The results indicate: decreasing trends of SPI are identified mainly in January

February and March

while increasing trends are dominantly concentrated in July

August and September. In the middle part of the study area

the number of months with increasing trends is more than in eastern and western parts. In addition

the eastern and coastal regions of Guangdong are characterized by increasing trends (wet tendency) of SPI in the rainy season (April to September)

and the majority portion of Guangdong shows decreasing trends (dry tendency) of SPI in winter. According to the results of REOF

there are four main anomaly sub modes in Guangdong

ie.

the Nanling

Leizhou Peninsula

the East and West Guangdong. All corresponding rotated principal components (RPC) of REOF indicate a wet-dry tendency in the rainy season

and all of them show a dry tendency in winter except the West Guangdong sub mode. 1.5-year and 2 to 3-year periods (significant at α=005 confidence level) can be investigated in all sub modes with the help of wavelet analysis.