Hi sebastian
I spent 2 weeks in Jordan last summer (at the Movenpick, next door to the Dead Sea Hotel...).
It was over 100 every day and I got a great tan and had a great stay...made lots of friends and enjoyed vsiting petra, amman and jeresh and the baptism site...and the scenery is breathtaking...watched the sun set over the west bank and jerusalem every evening

However, I was told that the weather in the winter is pretty cold and snow can fall too! I wouldn't expect it to be really warm until April time...the guys there told me they ski-ed last february!
Have a great time!
SJ