Rise in temperature is one of the predicted impacts of climate change with significant implications on water resources management. An attempt has been made to calculate the water requirement of crops in different agro-ecological zones of Palakkad district in humid tropical Kerala using the CROPWAT 8.0 model. Sensitivity analysis was done for a simulated rise in temperature from 0.5 to 3.0 °C keeping other parameters the same. The analysis showed that the total crop water requirement of all the major crops, like coconut, paddy and banana, increased with rising temperature thereby increasing the simulated irrigation water demand. The gross water demand inclusive of irrigation, domestic and industries will be 1,496 Mm3. The simulated gross water demand for an increase in temperature of 0.5, 1.0, 2.0 and 3.0 °C will be 1,523, 1,791, 1,822 and 1,853 Mm3, respectively. The maximum utilizable water resource available in the district is only 1,579 Mm3 and better water management, focusing particularly on improving the irrigation efficiency, has to be adopted to cater for the demands of the user sectors under changing climate scenario. A wide spectrum of climate change scenarios is also discussed in the paper along with guidelines for the future management of water resources.