Interesting question! I had to do a bit of research in order to find an answer to this question, and what I found was unexpected! When thinking about the hottest deserts, the Sahara (northern Africa) and the Mojave (southwestern US) deserts immediately came to mind. In fact, the hottest temperatures ever recorded by a thermometer on the ground were measured in Death Valley in the Mojave (56.7 Centigrade, 134 Farenheit) and in Libya in the Sahara (58 Centigrade, 136.4 Farenheit) click here

Interestingly, the hottest temperature ever recorded on earth was not measured by a traditional thermometer. It was measured by a satellite that detects infrared radiation, which is given off by things that are very hot and “radiate” energy. The winner for hottest desert (at least the hottest temperature ever measured on earth) is…

The Lut desert in Iran! In 2005 a NASA satellite recorded a temperature of 70.7 Centigrade (159.3 Farenheit). That is really, really hot! I have included an infrared picture of part of the Lut desert from the NASA webpage above. In this picture, the lighter colors are the hottest spots. The temperature “scale” is in Celsius temperature units, but it can be converted to Fahrenheit by this equation:

I have never been to the Lut desert, but I have been to the Gobi desert in Mongolia. The Gobi is very hot in the summer time, but very cold in the winter. I have also been to the coldest desert in the world– the Dry Valleys in Antarctica. That was really cold!

Well, that depends on how you define 'hottest'. The hottest surface temperature ever recorded on Earth was recorded in Death Valley, California, on July 10, 1913. The high that day reached 134 degrees Fahrenheit (or 56.7 degrees Celsius)! Death Valley is part of the Mojave Desert, which, along with the Sonoran desert, form one of the hottest deserts in the world.

The next hottest temperature readings were recorded in: Sudan (127 F), Iran (128 F), Israel (129 F), Mali (130 F), Tunisia (131 F), and Libya (131 F)

If you are wondering which desert has the highest AVERAGE temperature, then that would be in the Danakil desert of Ethiopia, with an average temperature of 93 F. For comparison, the highest average temperature in the U.S. is Key West, Florida, at 77.8 F. The average temperature in Santa Barbara is 61.1 F.

According to several sources, the highest land surface temperature ever recorded was 136° F in the Sahara Desert, at El Azizia, Libya, on September 22, 1922. Some people dispute this record, though, because of the way it was measured. Instead, they suggest that the highest temperature recorded was 134° F on July 10, 1913, in Death Valley, California, which is in the Mojave Desert.

These are records for a single temperature measurement, though, so they don't tell us how consistent temperatures like these are over time in the Sahara and Mojave deserts. To see which of the world's deserts consistently has the hottest temperatures, we'd need to look at temperatures recorded in each desert over time and average them.