New underground transportation infrastructures as subway and railway tunnels are increasingly being constructed under urban areas. These and other underground developments disturb the preexistent city constructions as monuments, buildings and other facilities. In the last decade several big underground infrastructures have been constructed, for example in London, Amsterdam, Paris, Beijing, Shangai, etc. In the city of Barcelona (Spain) a new 44 km subway line and the High Speed Railway city crossing were built. Monitoring systems have been widely used there to guarantee the safety of the city inhabitants, the workers, the urban buildings and other infrastructures. Robotic Total Stations and precision leveling have been systematically and intensively used. During these precision works, some thermal effects appeared occasionally in the auscultation results. We have to keep in mind that at some latitudes the sun insolation may introduce huge temperature night/day and winter/summer gradients. This `noise' due to temperature changes has reached up to 8 mm at some Barcelona locations. Thus, it might partly mask the movements due to tunneling, the main goal of the monitoring setup.