convert a closet???

[godzilabob]

Hi everyone...thanks again for all the advice beforehand.
I am wondering if it is feasible to convert a medium sized closet (5'x7') to a wine cellar...
I live somewhat near Napa, so it does get warm in the summer...It is a new home so it's fairly well insulated, but don't know what the temp might escalate to...
Winter without heating is about 55 degrees...
temp/humidity control necessary? how to do it???
anyone? beuller?
thanks!!!