The salt damage is one of the main decay features in archaeological sites and monuments. The Northern Theater of the Roman archaeological site of Jerash in Jordan is facing considerably this decay agent. The current study is a comprehensive evaluation of the main environmental conditions within the case study area with a detailed assessment of the soluble salt content at varied periods on the theater. The study extended to evaluate the relation between salts content and salt distribution with the main recorded environmental conditions. The current research fieldwork observation and data collection has shown that wind speed had a major role in salt crystallisation and distribution in porous building materials, and thereby in the ultimately stone decay rates. The study has also demonstrated the importance of using thermodynamic calculation in evaluation the salt distribution and behavior as major action in stating the preventive conservation measures in archaeological sites and monuments.