Actually this is a very good question with a deep answer.

First, the plants grow in a wide temperature range and humidity. In the wild, there is air movement and the roots are in the ground, two key elements to the answer to the question.

As long as the roots stay below 80 degrees and above 50 degrees F you are fine. The plant can take well over 115 if the roots are not overheated.

The humidity issue can be a problem in flower, but air movement and exchange is the key to this also...just like nature's wind. I had a week of 90% humidity and was very worried I would get bud mold on my almost done plants. Fortunately my fans exchanged enough air that there was no stagnation to allow mold to form.

So, there is no 'ideal' temperature or humidity, but there are factors that must be considered during a grow.