Ambient vibrations of a six-story lightweight timber frame building were measured under different environmental conditions in order to obtain the modal parameters of the structure. Changes in temperature and relative humidi-ty in timber can influence its response in terms of modal parameters. Namely, a moisture content change in the timber can affect stiffness, strength, and shape of the elements as well as the properties of the connections. Monthly measure-ments have been performed on a six-story lightweight timber frame building in Varberg, Sweden, built in 2021. The in-situ tests were performed using five bat-tery-driven data acquisition units with 14 uni-axial accelerometers. Additional-ly, the building is permanently monitored using temperature and humidity sen-sors, starting ever since its construction phase. The ambient vibration data have been analyzed using two different only-output methods. The results obtained under different temperature and humidity conditions were compared in order to assess the effect of the environmental conditions in the building. This infor-mation can be used to ensure the building meets safety and performance re-quirements, as well as to identify potential issues that may need to be addressed during building design.