Temperature

{thermometer}

Chemical reactions increase in organic materials when humidity and temperature rise. While moisture can catalyse chemical reactions, increases in temperature will accelerate the rate of these reactions.

For every 10 °C rise in temperature the rate of chemical degradation reactions in traditional library and archive materials, such as paper and books is doubled. Conversely for every 10 °C drop the rate is halved.
A hot and dry environment causes dessication and embrittlement of leather, parchment/vellum, paper, adhesives, as well as the adhesive binders in magnetic and optical media.
A hot and humid environment causes mould growth and creates a conducive environment for pests and insects.
Cold (less than 10 °C /50 °F) together with high relative humidity and poor air circulation will lead to dampness and eventually mould growth.