If you have a small batch of apples, a refrigerator or basement is probably the best way to store them.
If your basement isn’t cold enough, try storing your apples in insulated containers in an unheated building or outside in straw-lined pits.
Try lining your apple storage containers with perforated plastic liners to help prevent the apples from drying out.
Be sure to poke holes in the plastic to allow some air circulation even if your liner is just a plastic bag.
For larger amounts of apples, you may want to set up a humidifier in the basement, says W. C. Stiles, Ph.D., an apple researcher at Cornell University.
You can make your own humidifier by walling off a small area and hanging up burlap so that the bottom end dips into a pan of water, with a fan set up right behind the burlap sheet to blow the moist air throughout the cellar.
Just remember, though, that the motor of the fan (or a regular humidifier) will give off heat and may be enough to warm up your apples.
For storing, apples need an optimal temperature of 30°F to 32°F—just 10 degrees warmer, and they’ll ripen twice as fast.