Instead of increasing temperature, ETo decreased because of increasing relative humidity and decreasing sun-shine hours and wind-speed. Declining ETO and shorter growing season due to higher temperature decreased potential crop water requirement (∑ETC) of Boro rice. High variations in potential irrigation requirement for crop evapotranspiration (∑ETC − ER) of Boro rice among different districts are linked to variations in effective rainfall. Declining trends of net irrigation requirements of Boro rice. A warming climate does not always result in higher agricultural water use.