If you can't plant them outside I guess you don't have much of a choice. If they were mine I would put them in some damp soil or saw dust in a large container. That way there would be less of a chance of them drying out.

If they're wrapped in a way they won't dehydrate and your temps stay around that till planting time you should be fine. Most nurseries that serve the northeast dig in fall and refrigerate until spring. However in a heated space, even if it's cool it could get too dry.

I bought these from a NY State nursey. He has some of the best trees I have seen. Clean straight trunks on the trees, no scratches or injured trunks. He stores his graded apple trees in big wooden apple boxes that are filled with damp peat type-saw dust...(same ones are also used to store apples after picking.)
He does not water. I have seen other nurseries grade their trees and just periodically spray them with water, having their roots exposed in the refrigerated areas.

The location I have them in is not heated. It is cold. It is a cellar that is underneath my porch that I have an open window in. The temp in there right now is 40 degrees F. Tree roots are wrapped with thick plastic. But if I could pick a better alternative, there could be more saw dust peat in the package. He said they will be fine.

What is the name of your nursery and what's the diameter of the trees?

Wafler nursery, 5 foot whips & 5/8" well feathered trees.

You should be OK storing like this, just make sure they don't dry up,
being in a dark place also helps.
Kokos...no problem taking life material into Canada?

No problem Konrad, I didn't declare them. Just went through as normal. The trees are certified virus free wood, that is a top notch nursery. He told me he should be able to ship into Canada in 3 years. It's just a bunch of paperwork, nothing less. The trees are safe. The U.S. have strict standards producing this stuff.

Yup, I hear it's Canada that's having some trouble wiping out plum pox.

Canada is a joke brother. I find that the Americans respect my business better and know what I want and they fill my requests, no problem. In regards to fruit trees, the North Eastern American nuseries actually take time to package your trees and carefully wrap them to prevent them from drying out. Here in Canada I went to a nursery and they didn't even bother wrapping my trees for me in saw dust mulch, instead they put my trees in a garbage bag and they said see you later, and paying 13% TAX on them also, it was on the way I went...no care if the trees don't live for me or not. The American nurseries like: Wafler, ACN, do not have one single tick or scratch on their trees. Here in Canada the few I went to, one in particular there were scratches, dents in the trees.
For a while now, I support American business entirely, even bring groceries from the U.S. that last me a good while till I go back.