Global warming is occurring at an alarming rate and predictions are that air temperature (T_a) will continue to increase during this century. Increases in T_a as a result of unabated production of greenhouse gases in our atmosphere pose a threat to the distribution and abundance of wildlife populations worldwide. Although all the animals worldwide will likely be affected by global warming, diurnal animals in the deserts will be particularly threatened in the future because T_as are already high, and animals have limited access to water. It is expected that Saudi Arabia will experience a 3–5°C in T_a over the next century. For predicting the consequences of global warming for animals, it is important to understand how individual species will respond to higher air temperatures. We think that populations will not have sufficient time to make evolutionary adjustments to higher T_a, and therefore they will be forced to alter their distribution patterns, or make phenotypic adjustments in their ability to cope with high T_a. This report examines how increases in T_a might affect body temperature (T_b) in the animals of arid regions. We chose three taxonomic groups, mammals, birds, and reptiles (Arabian oryx, Arabian spiny-tailed lizard, vultures, and hoopoe larks) from Saudi Arabia, an area in which T_a often reaches 45°C during midday in summer. When T_a exceeds T_b, animals must resort to behavioral and physiological methods to control their T_b; failure to do so results in death. The observations of this study show that in many cases T_b is already close to the upper lethal limit of around 47°C in these species and therefore allowing their T_b to increase as T_a increases are not an option. We conclude that global warming will have a detrimental impact on a wide range of desert animals, but in reality we know little about the ability of most animals to cope with change in T_a. The data presented should serve as base-line information on T_b of animals in the Kingdom for future scientists in Saudi Arabia as they explore the impact of global warming on animal species.