Basic Wine Storage

Proper wine storage is critical to maintain the quality of your wine. How your wine is stored will directly effect the final flavor, color and character of each bottle of wine you purchase.
We know many bottles of wine you purchase will be consumed immediately or in the short term. However, even those kept for a few weeks or months can be positively or negatively impacted by the type of home wine storage you have. For most wine lovers, having the right kind of wine storage unit is imperative.
The most important consideration in proper wine storage is temperature. It’s also about these five factors:
Wine Storage Temperature Stability
In addition to maintaining the right temperature, properly stored wine allows for a very slight fluctuation of that ideal temperature. For wine to remain stable, it is recommended that your wine storage temperature not fluctuate more than 2º – 3º C or 5º F and that those fluctuations are rare. With each temperature fluctuation, outside air can seep into the bottle causing wine to lose its freshness.
Humidity
The ideal humidity level for home wine storage is between 60 to 70 percent. Low humidity can cause the cork to dry out and crack, allowing more air into the bottle. High humidity can create mildew or rot on the cork.
Ventilation
Outside air will seep into your wine bottles through the cork, so be sure there are no smells or odors coming from other substances stored nearby your wine for long periods of time. These would include cleaning solvents, paint or chemicals of any kind.
Light Level
Wine bottles and most wine coolers are tinted with dark colored glass to allow very little light to get to the wine. Wines like the darkness. Never store your wine in direct sunlight or in a well-lit room.
Storage Angle
Wine bottles should always be stored either horizontally, at a 45º angle with the cork facing down, or somewhere in between. This will keep the wine in constant contact with the cork ensuring no air gets into the bottle.

Source: http://www.basic-wine-knowledge.com