The Sahara Desert is a very hot and dry region of the world with an average temperature of 86 F in the cooler months and a high of 104 F for most of the months and it can even get as hot as 117 F in some parts of the year.
The sand can get pretty hot and likely can get as hot as 140 F or even hotter but I've never been to the Sahara Desert and never measured the temperature of the sand.
But I've been in sand before during hot weather and it has gotten pretty hot where I couldn't walk barefoot on it without burning my feet.
The sand doesn't hold heat in very well so at night the sand will start to cool down.