Here's a general idea:
* Hot Temperatures: Mustangs can handle very hot temperatures, even in the deserts of the southwest. They have evolved mechanisms to cope with heat, including sweating and panting.
* Cold Temperatures: They are also able to survive in cold environments, even in the snowy mountains of the west. They have a thick coat of fur that provides insulation, and they can huddle together for warmth.
* Extreme Temperatures: The key factor is not a specific temperature, but rather the ability of the horses to access adequate food and water.
In summary, there isn't one specific temperature that wild horses live in. They are very adaptable and can thrive in a variety of climates, as long as they have access to the resources they need.