Ideal is 20-25 degree Celsius and 60-80% humidity. Just for your information, with lower temperature ink viscosity increase as a result drop formation start to change. Usually below 15degrees ink become too think and you would not able to get print results. When it too hot then ink become more "watery" again you will have some kind of over sprays.
Another point to warry about with low humidity you increase static electricity on the media. With HIGH humidity material will absorb water in to it.