[Don Plumley]

55F is regarded as ideal cellar temperature. Colder than that and the wine won't develop. Warmer than 75 it will slowly bake. As others have said, rapidly moving temperatures are the biggest concern. A secondary concern is Humidity - it should be between 55-85% to help keep corks from drying out.

A simple insulated area will do a lot to keep temperatures in control as the wine itself is a biomass. The more wine packed together, the more stable the local temperature - good excuse to buy more wine.

I think a simple insulated box would go a long way to help the wine from hitting the 70's.