Cannabis’ temperature range is fairly wide, as it is a hardy weed that grows literally all over the world. By virtue of having an indoor grow closet, you have a lot more control over the “climate” in your grow closet than if you were growing outdoors.
Cannabis can comfortably tolerate a temperature range between 10°C (50°F) and 32°C (90°F) in your grow closet. Be aware, though, that the type of lighting you’re using in it, the amount of airflow, proximity to an exterior wall, and whether or not the space is air-conditioned can all influence the ambient temperature of your closet.
Speaking of airflow, it’s very important that you have at least one fan in your grow closet gently moving the air around 
and between your plants at all times. It doesn’t have to be a forceful gale blowing; it just needs to be enough to keep your plants moving slightly.
There are several good reasons for using a fan in your grow closet. First, the gentle breeze mimics an outdoor growing environment, and ongoing, gentle movement of your plants encourages them to grow thicker, stronger primary stalks and stems. This is nature’s way of preparing them to support the heavier weight of the big colas (buds) that will be developing in the later flowering stage.
Second, continuous air movement in and around your plants not only helps dissipate heat from collecting in any one spot, but it also prevents too humid air from setting up a mold- or fungus-friendly environment that would be very detrimental to your plants.
