I don't know if this is good or bad advice- but I started keeping a small bowl of saturated salt in my cooler. I don't have a wine cooler- it's just a large plastic cooler in my crawl space, lid closed but not latched. I keep a small bowl with maybe 1/4 cup salt (max) mixed with a little water (not so much salt dissolves, it just stays moist) in it, and at current temp = 55F, my humidity gauge reads a constant 75%. Last winter it read close to 90% humidity (probably crawl space was moister, or perhaps because the cooler temp was colder then, about 50F? I don't know- I suck at physics).