December sees temperature averaging 26 degrees in Dubai. The milder temperatures make December peak season for travel, so early booking, especially for Christmas and New Year is essential.
There may be a couple of days in December when some rainfall is seen in the form of a fleeting shower.
In the mountains the temperatures are a little lower and temperatures at night can be feel cold once the sun has set. The desert also can be very cold at night, so warm clothing is essential.