It depends on the winter temperatures, and whether or not it is protected or sheltered. If it is left in the open on a night with single digits and some wind, you're probably going to lose the palm.

That's because they are not hardy there long-term without super shelter.

Hello,

I think your main problem is the humidity during winter . Here in Mashhad/Iran we have the same problem too. I saw a lot of Phoenix dactylifera´s but i havent seen a big one.