I was never good at science but as a cigar nerd, I wanted to understand relative humidity (RH) as much as possible.  My collection has grown at a good pace and I want to eventually have a very large collection so this is something that was important for me to understand.  I may not have this 100% but I'm pretty sure that this is a solid concept on what we should all strive for.  If you're a science nerd and completely understand this and notice something incorrect, please let us all know.  There are so many formulas to get an exact figure but it's so far above my head that I cannot grasp it.  There are important points that everyone should be able to understand.


This isn't anything absolute, just some food for thought.  To be honest, I'm probably over complicating things.


First thing is first though, you need to get good hygrometers and calibrate them!  The salt test works but if you really want to get into this, get a Boveda calibration kit.  You can also just use a Boveda pack you already have and just put them in an airtight container and calibrate to that RH.


So, with all that out of the way, here is what you need to understand about RH!



A pretty common topic on most cigar forums is:  "What Relative Humidity (RH) do you store your cigars at?"  People who respond say what RH they store at but the information is useless without knowing the second part of this question.

The better and more appropriate question is:  "What temperature and RH do you store your cigars at?"


The reason that the second question is the more important question is RH is relative to something... and that something is temperature.  Why is this important though?  When you smoke a cigar or pipe, what you are actually tasting is the oils contained within the tobacco (assuming that the tobacco is not cased with flavorings ).  The tobacco heats up and oils are released.  When you draw on your cigar or pipe, the oils are carried with the smoke over your palate.  Maintaining an acceptable humidity level is essential to maintaining those flavorful oils.  When a cigar drys out, those oils are lost.  At the other end of the spectrum, when a cigar becomes overly humidified, mold can form and tobacco beetles can hatch.


So, what is an acceptable humidity level and temperature for me to store my cigars at?  That is a good question and will depend on what tools you have available to you.  If you're using a regular humidor or anything that you can not directly control the temperature, you should ensure that it is in an air conditioned space away from windows so that direct sunlight will not hit it.  If you have a temperature controlled cabinet or wineador, you have much greater control over how much water will be in the air within your humidor.


For those who are familiar with habanos, you already know this and for those who aren't familiar...  Habanos S.A. (the Cuban owned distributor of cigars) includes an internal notice, in every box, to tell you how to care for your cigars.  The important sentence is: Please keep them in a humidor well away from products that emit strong odors and in the correct conditions of temperature (16dC-18dC) and relative humidity (65%-70%).  




Cuba is widely recognized as the authority when it comes to cigars.  How many countries have scientific research laboratories dedicated to nothing but tobacco?  As far as I know, there aren't any countries other than Cuba.  I don't know about everyone else, but if you have a decent cigar collection, this is incredibly important information from the worlds leader in cigar knowledge and I do my best to follow it.  So lets look at what's recommended but first, since this is 'Murica, lets convert C - F.  16dC-18dC equals 60.8dF-64.4dF.  For simplicity, lets just say 61dF-65dF.


Relative humidity is defined:  The ratio of the partial pressure of water vapor (H2O) in the mixture to the equilibrium vapor pressure of water at a given temperature.  


What does that mean to us?  To me, It means nothing other than the actual amount of water in air is a variable depending on pressure and temperature.  The chart below is a good illustration of how much water is actually in the air at given temperatures.




So, what I've concluded is this:  The more important aspect for cigar storage is, how much water is necessary to maintain the oils within cigars?  By just eyeballing the above chart and using the ideal storage conditions, the answer is around 7-9 grams of water per kilogram of air.


If you were to store your cigars in a desktop humidor on your desk directly in sunlight, it is not unrealistic to think that the temperature of the air in your humidor and your cigars will be 30dC (86dF).  If you store your cigars at 70% RH, the amount of water will be around 20g/kg of air!  Yes, you're at 70%RH but there is way too much water!  You're likely to have burn and draw problems with your cigars and have drastically increased the chances of tobacco beetles hatching.


Experiment around a little bit and figure out what works best for you.  I've personally found that I like my cigars just a touch dryer than that the internal notice recommends.  I've found that I can differentiate flavors better and I get a better burn and draw when stored at 66dF and 62%RH.  On a side note, given the slightly higher temperature and slightly lower RH, the actual amount of water in the air is still right around the 7 gram/kg mark.


That takes care of relative humidity, now lets talk dew point.  This is important if you have a temperature controlled humidor.  


Another common thread is "Help! I have condensation in my wineador!"


Dew point is the temperature at which water vapor in air turns into liquid water at the same rate at which it evaporates.  At temperatures below the dew point, water will leave the air.  The condensed water is called dew when it forms on solid surfaces and is called either fog or a cloud, depending on it's altitude, when it forms in the air.


So, why does dew or condensation form inside a wineador?  Simply enough, there is too great of a temperature difference between the environment the windador is stored in and the temperature inside the unit.  For example, the glass can become hotter than the set temperature because of ambient temperature as well as the sun if it's stored in direct light.


Dew Point Calculator:



Using my personal example, my wineador is never in the sun and the temperature of my room is at 76dF where I store my cigars at 62%RH.  Using the above calculator, the dew point is then 62.06dF.  I cannot set my wineador at 62dF or below, otherwise I will risk condensation.


Now let's say that my wineador is in direct sunlight so that the sun heats the unit to 82dF.  Given the storage at 62%RH, the dew point is now 67.7dF.  Most wineadors have a maximum temperature setting around 66dF so you will not be able to get above the dew point.  You're likely to experience condensation and get soggy cigars.


Easy enough, right?


Again, all that is as I understand it and if you have a better grasp or notice something wrong, please share.