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What makes a place a desert? Surprisingly, it is not "hot and dry" weather. Actually, it is just "dry" weather that makes a desert. A desert is generally defined as a place the receives less than 10" (254 mm) of precipitation each year.
Temperature has no bearing on whether a location is called a desert or not. The "coldest" desert in the world is Antarctica with an annual average of 2" (51 mm) of precipitation (mostly snow) each year.
To discover about more about deserts and climates, go to JetStream - an Online School for Weather.