One may say that you can visit the United Arab Emirates all year round.
It may be truth, but I recommend to avoid summer months, i.e., June, July, August, because it’s very hot there. Even air-condition is almost everywhere, you may feel exhausted because of the heat.
And I think, it’s nice to escape cold December and enjoy warm days in the Emirates. 🙂
Actually if you want really nice weather, Oman and its mountains between October & April.