Sleeping All day
In order to avoid the heat of day, many animals sleep all day and are most active during cooler twilight hours or at night (Nocturnal animals). Examples of these include bobcats, hyenas, and coyotes.
This picture is of a hyena, who are night predators who are most active in the twilight hours.
A good way of avoiding heat is going underground. This keeps animals out of the sun, and the temperatures underground lower than the temperatures above ground. Examples include kangaroo rats and other desert rodents.
This picture is of a Kangaroo rat, a desert rodent who burrows.
Some animals simply adapt to extreme temperatures by having a higher tolerance. For example, the antelope squirrel can tolerate body temperatures of up to 104 degrees Fahrenheit, which is equivalent to a bad human fever.
This picture is of antelope squirrel, who have a higher tolerance to heat and can tolerate body temperatures of up to 104 degrees Fahrenheit.
Many animals have adapted to better get rid of heat / get heat off of their bodies. One example of this is birds; many birds can decrease the insulation given by their feathers. Some animals, like jackrabbits, have long body parts that provide the benefits of having a high surface area : volume ratio to keep them cool.
This is an image of a desert bird, which can increase/decrease the amount of insulation given to them by their feathers.
Too avoid the worst of the extreme temperatures, many animals lower their body temperature and heart rate, entering an almost dormant state. They will stay this way for many months, remaining inactive until the brunt of the temperature has gone. Examples of hibernating animals include bears, badgers, bats, chipmunks, and frogs. Examples of estivating animals include snails, crocodiles, hedgehogs, tortoises, and various different birds.
This image is of a brown bear, who hibernate during the winter.