This study aims to monitor the temporal development of soybean crops using Sentinel-2 multispectral imagery and the Normalized Difference Vegetation Index (NDVI). Five image acquisition dates were selected to represent key phenological stages of the crop: emergence, early vegetative stage, flowering, pod formation, and maturation. NDVI maps and difference analyses between consecutive dates were generated to evaluate variations in vegetation vigor over time. The results showed an expected pattern for irrigated soybean: NDVI values increased during early growth and peaked during flowering, followed by a gradual decline toward maturation. The spatial resolution of the images allowed the identification of field-level variations, including planting row differences and the effects of machinery tracks on plant development. A key contribution of this study is the establishment of a reference multitemporal NDVI pattern for soybean under irrigated conditions. This reference can serve as a baseline for comparing non-irrigated fields, supporting the detection of anomalies caused by stress factors such as water scarcity, pests, or diseases. The method stands out for being low-cost, accessible, and easy to interpret, which makes it valuable for both large-scale and smallholder farmers. Although NDVI is effective in identifying variations in plant vigor, it does not indicate the health loss of plants compared to a good health one and should be used in combination with other agronomic information. The approach presented here reinforces the potential of NDVI-based temporal analysis as a practical tool for crop monitoring and precision agriculture in regions with irregular climatic conditions.