Two-layered Air Force organic coatings are designed with the topcoat functioning as a barrier against the environment and the primer providing adhesion between the topcoat and the substrate as well as promoting chromate passivation. In standard testing methods such as salt spray and QUV/Prohesion, periodic testing of coatings is performed by ex-situ electrochemical experiments. The primary purpose of these accelerated testing procedures is to rank coating performance under simulated weathering conditions. The conventional approach for these electrochemical impedance spectroscopy measurements requires that a conductive medium be in direct contact with the exposed coating. As such the influence of the atmospheric humidity on the performance of the coating is lost. The inclusion of embedded sensors within two-layered coating systems allows in-situ monitoring of the coating primer/substrate electrochemical properties. The influence of atmospheric humidity on the electrochemical properties of the primer/substrate of an Air Force urethane topcoat/chromate epoxy primer is reported here. The experimental procedure involved exposure of coated AA 2024-T3 substrates to different humidity levels at several temperatures. Electrochemical impedance spectroscopy was conducted to assess the electrochemical properties of the primer/substrate beneath the topcoat. The analysis of the data is presented to demonstrate the change in the barrier property of the topcoat in response to humidity and thermal conditions.