Caiman crocodilus is a widely distributed species in the Neotropics; however, studies of incubation temperatures in wildlife are uncommon. Incubation temperature in four nests of Caiman crocodilus were measured with a digital thermometer, in the National Wildlife Refuge Caño Negro, Costa Rica. Average temperatures in these four nests (no. 1-4) were 32.13 + 0.92 °C (no. 1), 32.46 + 0.77 °C (no. 2), 33.60 + 0.95 °C (no. 3), and 31.78 + 2.30 °C (no. 4). Temperature variations recorded showed higher temperatures than those reported from other studies in Caño Negro. The temperatures registered in this study will lead to a higher proportion of males within the caiman population, reducing the number of future reproducing females and, therefore, in the population viability.