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.”
[U]Best temperature and humidity levels for printing are[/U]:
59 to 77 °F (15 to 25 °C)
40 to 60% Humidity (without condensation)