For water resources to be sustainable, it is very important to predict the impacts of climate change very well and develop strategies for adaptation. This study aims to model the impact of possible climate change on plant water consumption (ET_c) and irrigation water requirements (IWR) in watermelon cultivation. To achieve this goal, 36 scenarios were created considering the increase and decrease of minimum and maximum temperatures (1, 2, 3 ^oC) and precipitation (10%, 20%, 30%) in the climate data of the reference period 1940-2024 in watermelon cultivation in Tekirdağ and the effects of possible climate change on ET_c and IWR were modeled in line with these scenarios. As a result, it was determined that ET_c values will vary between 376.9-447.2 mm season^-1, and IWR values will vary between 246.0-367.8 mm season^-1. When temperatures increase by 1, 2, and 3 ^oC compared to the reference period, ET_c values increase by 2.8%, 5.7% and 8.6%, respectively, while when temperatures decrease by 1, 2, and 3 ^oC, ET_c values decrease by 2.9%, 5.7% and 8.5%, respectively. IWR values range from -18.5% to 21.9% compared to the reference period. While ET_c varies in direct proportion with temperature change, IWR varies in inverse proportion with precipitation change. It is thought that this study will guide managers, practitioners, and decision makers.