Is My Horse Cold?
If your horse has a thick winter coat and some shelter, they don’t mind the cold!
In the absence of wind and moisture, horses tolerate temperatures at or slightly below 0° F. If horses have access to a shelter, they can tolerate temperatures as low as -40° F. But horses are most comfortable at temperatures between 18° and 59° F, depending on their hair coat.
Here’s more great information from University of Minnesota Extension:
https://extension.umn.edu/horse-care-and-management/caring-your-horse-winter