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Estimation of potential evapotranspiration (PET) at sub-taluk level during different seasons gains importance in the existing scenario of climate change and aberrant weather conditions in the chronic drought prone state of Karnataka. The PET (water need) estimations in different sub-taluks of selected districts under different Agro-climatic/Agro-ecological regions indicate that, the water need was high in semi-arid/arid districts than the humid districts. The average PET of selected districts was in the following order: Koppala > Chitradurga > Dakshina Kannada > Kodagu. The variability in PET was observed among the sub-taluks of the same district and different districts. In general the average PET during 9-22 SMW (summer) was relatively higher than the other seasons, in all sub-taluks or districts. The comparison between normal PET and actual calculated PET in the present study shows that the normal PET values were higher in all the seasons of all the districts except in the south west monsoon season (22-39 SMW). It indicates that actual PET is a better estimate since it provides the actual water need specific to the sub-taluk area and season. Hence these actual PET values are better tools for developing location/season specific indices in drought assessment and crop water management planning.