This study aims to assess the impact of the targeted scene and environmental variables on in situ longterm thermal monitoring by infrared thermography. It also addresses projection errors arising from camera perspectives and digitization. Over a span of 3 years, extensive measurements were conducted at two instrumented test sites, yielding a valuable dataset for analysis. The paper begins by introducing and discussing the model used to convert the collected data into surface temperature estimations and its associated parameters’ sensitivities. Subsequently, it delves into the effects of camera resectioning on infrared measurements. Finally, the study investigates the influence of environmental parameters and proposes a strategy to correct for these effects, with and without additional sensors (opportunistic data) and additional in-situ measurements. Finally, a discussion is proposed and perspectives are addressed.