Caring for your Piano – from Steinway South Africa

AMBIENT CONDITIONS
Wood and felt are highly sensitive to extreme changes in temperature and humidity. During the heating period a standard good-quality humidifier should be used to control and regulate humidity. The most favorable environment for your piano is a relative humidity ranging between 45% and 70% and a constant temperature of approximately 20˚C. Sudden fluctuations in temperature must be avoided as the tuning and regulation might be influenced negatively.

via Caring for your Piano