According to the University of California - Santa Barbra, ice cream will melt at about 31 degrees Fahrenheit or -3 degrees Celsius. The freezing point of water is about 32 degrees Fahrenheit, but the ice cream is affected by the salt content. Adding salt to a liquid lowers the freezing point of the substance.
The reason why salt affects the freezing point of liquids is because of the way liquids freeze. The molecules in a liquid are constantly moving, but as the liquid becomes colder, the molecules slow down causing it to freeze. When salt molecules are added to the liquid, the two molecules combine so that more heat must be removed in order for the liquid to freeze.