How to store: Peaches and nectarines will continue to ripen after they've been harvested if you leave them at room temperature. They should never be refrigerated until they are fully ripe. Chilling them before that will result in fruit that is mealy and flavorless.
What is the best way to store nectarines?
Store nectarines at room temperature until they're ripe.
They should also emit a fragrant smell when they've reached ripeness. If you need them sooner, put your nectarines in a paper bag to ripen faster. Nectarines produce a gas called ethylene which ripens them faster when stored in a paper bag.
Can nectarines be left out?
So if you buy peaches, plums or nectarines that are still a little firm, just leave them at room temperature for a day or two. They'll soften right up. Then you can put them in the refrigerator.