The degree and the speed of the temperature change are critical. A gradual change of a few degrees between summer and winter won’t matter. The same change each day will harm your wines by ageing them too rapidly.
Avoiding wide temperature fluctuations is a critical rule when storing wine for any length of time. A sticky deposit can quickly form around the capsule if the wine is exposed to sudden temperature fluctuations.
The continual expansion and contraction of the wine will, over time, damage the ‘integrity’ of the cork. It’s like having the cork pulled in and out every day. When this happens, minute quantities of wine may be pushed out along the edge of the cork (between the cork and the bottle neck) allowing air to seep back in. Once the air has come in contact with your wine the irreversible process of oxidation begins and your wine will be ruined.
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