okunen said:
"This passage is one of the oldest false rumors around. Anyone with even a passing understanding of cigar storage should know that. While it is true that it is harder to get cold air to hold moisture, the actual relative humidity should not vary with regard to temperature. That's why it's called "relative."
This is correct, insofar as one should keep relative humidity at a consistent percentage regardless of temperature. For example, if you like your cigars at 65% at 70 F., and the temperature drops to 65 F., you should keep them at 65%. In fact, if you are using PG or a beads the amount of vapor will adjust automatically to maintain RH at the same percentage.
True, air holds more moisture at a higher temperature, but that is only part of the story.
Here is a more expansive explanation from the ICG FAQ (http://www.cigargroup.com/faq/#5.0a):
Here's a more scientific explanation debunking the myth of varying humidity from David E. Patton, Ph.D. at the Department of Physiology, UCLA School of Medicine...
"There has been extensive discussion on A.S.C. concerning the effects of temperature on humidity and its application to proper cigar storage. Much of the confusion concerning these concepts comes from not understanding what is happening at the molecular level. My goal is to explain some of the relevant concepts and then to put the concepts together in such a way as to give an intuitive understanding of how they relate to cigar storage.
Cigars are made from tobacco leaves. Tobacco leaves (like most plant material) consist primarily of carbohydrates and proteins. Protein and carbohydrate molecules contain many binding sites for water molecules. A certain proportion of the water binding sites need to be occupied by water molecules in order for the tobacco leaves to be adequately pliable, to burn properly and to age properly. So when we think about humidity as it relates to cigar storage, the most relavent factor to consider is: are the correct proportion of water binding sites occupied? Water molecules bind to other molecules via hydrogen bonds. Van der Waals interactions also participate. This applies to water bound to protein and carbohydrate molecules (e.g. tobacco leaves) or to other water molecules (e.g. liquid water). For the purposes of this discussion, water bound to tobacco leaves will be treated like liquid water.
Temperature is the main factor determining whether a water molecule will be more likely to be in either the gas or liquid (or bound) phases. This is because at higher temperatures, water molecules (like any other molecule) will have more kinetic energy. The more kinetic energy a molecule has, the higher its probability of being in the gas phase. This is because it will have sufficient kinetic energy to break out of the hydrogen bonds and Van der Waals interactions that would otherwise keep it bound. At lower temperatures molecules have less kinetic energy so when they collide with a carbohydrate molecule, for example, its kinetic energy is insuficient to break away from it. The important point here is that at higher temperatures, a water molecule is more likely to be in the gas phase and less likely to be bound. At lower temperatures a water molecule is more likely to be bound and less likely to be in the gas phase.
Another point that needs to be explained here is the concept of relative humidity. Simply stated, relative humidity is the ratio of the concentration of water in the gas phase divided by the maximal concentration of water the air can hold (the saturating concentration) at a given temperature. Air holds more water at higher temperatures. Therefore, if you hold the relative humidity constant and increase the temperature, the concentration of water molecules in the gas phase will increase. If you think about this superficially you may think that because the concentration of water molecules increases in the gas phase as you increase the temperature (holding relative humidity constant)that your cigars will become over-humidified. This is WRONG. Remember, as you increase the temperature, the water molecules are less likely to be bound to the tobacco and more likely to be in the gas phase. Thus, to keep the same proportion of water binding sites in the tobacco occupied by water molecules, the concentration of water molecules in the gas phase must be increased when temperature is increased."
Again, cigars should be stored at 70 - 73% relative humidity, regardless of temperature. Period.
