Temperature has an important influence on pitch. A cold instrument will tend to play flat, while one exposed to relatively high temperatures (e.g. as a result of prolonged exposure to sunlight) will tend to play sharp. The air temperature inside the bore, rather than the instrument itself, is the critical factor here. Because cold air is denser than warm ari, the air moecules provide greater resistance to the sound vibrations and thus lower the pitch.

Metal instruments warm up and cool down faster than those made of wood. Those with large bores and longer tubing take even longer to change temperature. This is the reason why the intonation of the tuba section in particular should be checked often during rehearsal and performance. Complicating matters further is the fact that a steady rise or fall in room temperature does not have a uniform effect on intonation across the ensemble. As the temperature rises or falls, the pitch deviation of the band's larger instruments will be wider than that of the smaller ones.

Manufacturers specify a room temperature of 72°F (22°C) as ideal for both tuning and performance. Unfortunately, such temperature conditions are not always possible in performance. Even so, the intonation problems associated with variations in air temperature represent a powerful reason why bands should tune-up on the stage and not be entirely dependent on back-stage tune-ups.