My cellar ranges 64 degrees in winter to about 75 in summer. My wines are keeping very well and I try to drink most within 3-5 years.
If it gets warm in summer, you can put a blanket over your rack to keep the temp consistent. Keep the more expensive wines on the bottom shelves where it's cooler. It's best if the floor is concrete; that helps.
Once you open your red wine.... let it breathe for at least 30 minutes before drinking. This has nothingto do with the storage but it's something most people don't have patience for.
I have been taught that Bordeaux wine will last [10] years under these conditions. The better the vintage, the longer it will last.
If you have an apartment, you can keep your wine in a closet during winter do nothing. In summer, it would be smart to air condition that room the closet's in. The humidity thing is just about the corks drying out. But the technology today keeps those corks in excellent shape in dry or humid weather. The secret is: no SUDDEN temperature change.
Hope this helps!
Cheers!