Humidity is as important as avoiding heat and light when storing and preserving your wine. You need to keep your wine in a storage area that is moderately damp. The humidity helps keep the cork damp and prevents it from drying out. If the cork dries out and oxygen hits your wine, it's just as though you opened it; the wine will have oxidized and turned only a few days after the air got to it.
Another way of keeping the cork damp is by keeping the wine bottles horizontal, tilted slightly toward the cork, which allows the wine to keep the cork damp. Too much humidity, though, and you could cause molding on the cork, which might creep down through the porous cork and invade the wine. It's best to keep your humidity between 60% and 75%. The humidity also helps to keep the wine cool and a humidity control feature is typically included in most models of wine cooling units.
