If you come around here and and are caucasian, You will fry in the sun - Use sunscreen, or your skin will die. It's simple, cover up. Covering the skin, so the sun does not shine directly on it will also keep you cooler, loose fitting, light coloured, pure cotton is the best. It's also very effective to avoid travel for 3 hours in the middle of the day. Siesta's, or a spell in a pub from midday to 3 are great ideas.
I draw the line at 40 degrees Celcius, but everybody is different.
I agree, deserts are amazing places, but hard to carry enough water for.