Correct storage temperature is the single most important subject to consider for wine collectors, with a standard of 55 degrees Fahrenheit for long term storage generally agreed upon. Jancis Robinson, Master of Wine, and editor of The Oxford Companion to Wine, in the 2nd Edition (1999) suggests avoiding “temperatures more than about 77 degrees F at which time the wine may be spoiled and forever afterwards taste ‘cooked.’” (NB this particular reference was removed as subsequent editions evolved.)
Briefly, exposure to warmer temperatures will accelerate the evolution of wine, and in our experience, short-term exposure to very high temperatures can also cause a wine to also develop ashy, metallic, unpleasant notes, and deteriorate extremely quickly once opened. Heat also causes liquid to expand, so with bottles stored on their sides, this may stain corks and cause protruding corks and/or leaking bottles.
We are often called in after a heat event, like a house fire or cooling going off during a hot summer. We can make determinations as to the affect of the collection by tasting a few select bottles. Fortified wines and dessert wines usually cover heat affect more, due to their sugar content and/or higher alcohol by volume (abv,) and frequently bold, tannic red wines can as well, with light white wines and sparkling wines more vulnerable. But sometimes this is not the case, so we choose wines to taste from a wide array of grape varieties, regions, ages, quality levels, and more.
Humidity is also a factor for proper storage, though not necessarily relating to the wine inside the bottle, but it can cause loose and wrinkled labels, which will negatively affect a wine’s value.
A note: please be cautious of natural cellars — we have had numerous clients who have sworn that their below-grade basement is “always cool.” But frequently these areas might reach low 40s F or get up to mid-to high 70s F (which seems cool when it’s 90+ outside,) and this fluctuation is also detrimental to a wine’s storage. In fact, with even a few years of these fluctuations, the wine may deteriorate quite quickly.
It is also generally agreed that wines with natural corks should be stored on their sides, as this allows the liquid inside the bottle to remain in contact with the cork, preventing it from drying out. However, spirits should be stored standing up, as the much higher alcohol by volume can actually eat away at the cork over time.
But if you are collecting wine, be it casually or as a serious investment, temperature-controlled storage is a must, to ensure the wine evolves as it is supposed to.