Humidity DOES matter when storing and aging wine over long periods of time. The ideal range for humidity is 50 to 70 percent. Not enough humidity, and the outside of the cork could dry out and shrink, leading to ullage and possible oxidation of your wine. Too much humidity, and the wine bottle labels might get moldy and/or peel off.
If you live in a dry area, it’s especially important to cellar your wine in a sealed environment. That way, you can add moisture inside the wine cellar and the moisture will remain inside. To add moisture, try placing a shallow dish of water with a sponge inside the wine cellar, or spray a mist of water from a water bottle inside the wine cellar.
If you live in a humid area, make sure that the cooling system in your wine cellar will remove excess moisture from the air. For more information about the proper conditions for long-term wine storage and aging, see avoid common mistakes when purchasing a wine cellar.