Climate changes can influence the genetic diversity of forage plants, which may contribute to the improvement and development of new species. Therefore, this research aimed to evaluate the influence of temperature increase on the genetic diversity of Macroptilium accessions based on morphoagronomic descriptors. The experiment was carried out in a growth chamber in a 2×16 factorial arrangement (temperature regimes x Macroptilium accessions), with the temperatures consisting of T1 (20–26–33 °C) and T2 (24.8–30.8–37.8 °C) and 16 accessions. Eleven morphoagronomic descriptors allowed estimating the diversity among accessions. The measurements of genetic dissimilarity enabled us to observe the genetic distance between the studied materials, standing out the accessions T1.M3 and T2.S4 as the most divergent (446.01). The morphoagronomic descriptors percentage of leaves and stem diameter were the most efficient for estimating the diversity between access. Genetic variability points to the adaptation of Macroptilium accessions in the climate change scenario. The accessions more divergent can be explored in genetic breeding programs for the species aiming at the expansion of genetic variability as an adaptation mechanism to heat stress.