Night temperatures should be kept above 60F to prevent marijuana plant stress. During the marijuana flowering phase drop the temperature further to stimulate flowering hormones and reduce stem elongation. Low humidity causes stress on marijuana plants.
It's recommend 50-60% humidity until the final two weeks of marijuana flowering. At this point, the humidity should be lowered as much as possible to encourage the plant to seal and protect itself with additional resin.
By dropping both the temperature and humidity in the final two weeks of marijuana flower will convince the cannabis plant fall is over and winter is any day now.
73-78?F (23-25?C) temperatures, 40-55% humidity, 1,500 ppm CO2, constant air flow and aeration, and scrubbed air.
Optimal Temperature:
Between 70 - 85 degrees Fahrenheit (21 - 29 degrees Celsius). [source;unk]
hope this answers your Q