g/m3 = grams per meter cubed.
I'll paste a small bit of text from a popular website below, but first I want to say that I think it is an awful idea to try to adjust RH to suit temperature. If your humidity is set high (to accommodate low temp) and you have an upswing in temperature, you could over humidify really quick, which would be really bad. For me it's much easier to store my smokes in a an area of the house that will see temperatures in the zone I'm looking for (65 to 72). I'm in the Northeast, so in the summer the humidor and coolidor are in the basement (so it's still cool when the AC is off). In the winter the smokes go upstairs since the basement heat is not always on.
I guess this is just a complicated way is saying that if you work to control rh because you want to store and age your cigars, don't completely ignore temperature.
From the website:
The ideal storage condition for a cigar are approximately 70% humidity at 68 degrees Fahrenheit. Air at different temperatures will hold completely different amounts of moisture. Warm air can hold a tremendous amount of moisture. If your cigars are stored in a warm place, you will have to continuously add water to the humidifier. The result will be very spongy cigars. Cold air holds almost no moisture. Air with 70% humidity will be dry at freezing temperatures. Relative humidity is defined as the percentage of the maximum amount of water that air can hold at a given temperature without condensation. As a general rule, when the air temperature is reduced from 68 degrees by one degree, the humidity should be increased by 1%, and vice versa. Therefore, if your cigars were stored at 58 degrees Fahrenheit, the humidity should be kept around 80%.
