Infectious diseases in wildlife threaten not only those species but also domestic animals and human health, necessitating strategies to prevent pathogen spread. The natural decomposition of carcasses may lead to pathogen inactivation due to associated increases in temperature and changes in the pH of the carcass and in the surrounding soil. In this study, the internal temperatures of 64 decomposing wild boar carcasses, the pH in the topsoil beneath 74 carcasses, and the pH of muscle and rectal tissue from 12 carcasses were monitored throughout the decomposition process. Carcass temperatures increased during decomposition, frequently exceeding 30 °C during aerobic decomposition in summer (maximum 58 °C). The pH in the carcasses increased until skeletonization, ranging from pH 4 to above pH 8. Soil pH also continuously increased during the decomposition, reaching a pH above 9 and remaining stable for at least 30 days post-skeletonization. The information on natural carcass decomposition processes provided by our study can serve as a basis for future studies to assess if elevated carcass temperatures and pH changes are sufficient for pathogen inactivation. However, our results suggest that, in most cases, neither the increase in carcass temperatures nor the changes in pH exceed the thresholds required to inactivate African swine fever virus.