Generally speaking, it’s best not to store nectarines in the fridge until they’re fully ripened since putting them in the fridge too early can delay the ripening process and impact their overall flavor and texture. You can tell if a nectarine is ripe by pushing down on the skin with your fingers. If it’s soft and bounces back, then that typically means that it’s ripe. At this point, you can store the nectarines in the fridge.