Almost all paint these days is water-based in some way, and this means you can’t store it over winter in an unheated space. Freezing temperatures might not always affect the properties of paint, but it usually does. And even if the paint seems to be fine next spring, you wouldn’t want to find out that it actually doesn’t perform properly after you’ve gone to all the trouble of applying it. So unfortunately, heated storage is required as we see true oil based paints become less and less common. Wherever you end up storing your paint, you’ll find that it keeps best if the cans are stored upside down. In my experience this keeps the paint fresher, and less likely to form a skin on top. Just make sure that your lid is sealed properly beforehand to prevent paint leakage.