Summary Globally, coastal cultivation regions (CCRs) are facing irrigation water shortages due to the impacts of climate change (ICV). CCRs have repeatedly suffered from saline irrigation water, increases in temperature, and reduced rainfall, resulting in irrigation water shortages. The aim of this study was, therefore, to evaluate the impacts of weather variables on the rice water requirement (RWR) in CCRs in Kien Giang Province. The response of rice grain yield to weather variables was estimated by simulating the AquaCrop model under different crop cultivation schedules (CCSs). These schedules involved advancing or delaying the sowing date by 30 days compared to the current common sowing date (baseline) for winter-spring (WS) and summer-fall (SF) vegetation seasons. The AquaCrop model demonstrated accurate simulation capabilities, as indicated by the high correlation values of statistical error indexes during the validation and calibration procedures. The findings revealed that rice grain yields would enhance up to 7.8% and 5.6% compared to the baseline when CCSs involve sowing 20 days earlier for WS vegetation season and are advanced by 20 days for SF vegetation season. Overall, modifying CCSs for coastal rice paddies in the study area, while considering weather variables, would have a positive contribution by mitigating the adverse effects of ICV.