Too hot and too dry is the worst for a printer, and can easily cause clogging and other ink flow issues, as well as problems with paper.
As per the Epson 4900 user guide:
"Avoid places subject to rapid changes in temperature and humidity. Also keep this product away from direct sunlight, strong light, heat sources, or air conditioners."
Best temperature and humidity levels for printing are:
59 to 77 °F (15 to 25 °C)
40 to 60% Humidity (without condensation)