Global warming has led to weather changes that can shift the sowing date of plants and affect their yield and irrigation needs. To investigate this issue, this study utilized the SSM Crop model to calculate climatic variables during the growth period, as well as to assess yield and irrigation requirements. The study considered seven scenarios involving a 15-day delay in the sowing date of both rainfed and irrigated maize, starting from May 1. This approach allowed us to examine changes over 32 years in the Gorgan region, using trend and mutation tests. The results indicate that climate changes during the growth period have led to an increased need for irrigation. However, the impact of climate change is such that both rainfed and irrigated maize cultivation are experiencing significant decreases in yield. Due to reduced precipitation and rising temperatures, the maize growing season in the region is becoming drier. These conditions result in decreased transpiration for rainfed agriculture, while in irrigated agriculture, evaporation and transpiration are increasing due to the need for irrigation. Due to a decrease in yield, water use efficiency is also declining. For fully irrigated crops, early planting is advised to mitigate the impacts of climate change. In rainfed agriculture, farmers may consider either early or late planting. In conclusion, while annual temperatures have risen, there has also been a significant reduction in precipitation during the growing season, which negatively affects maize yields as a result of climate change.