Milk freezes at 31.06 degrees Fahrenheit. Water freezes at 32 degrees Fahrenheit, but the presence of water-soluble substances, such as those contained in milk, bring down the freezing point to below that of water.
The exact freezing temperature of milk varies depending on the concentration of the water-soluble substances. If milk is diluted, it freezes at a temperature close to 32 F. Higher concentrations of substances and solvents brings the freezing point lower than 32 F. Certain factors also affect the freezing point, such as diet of the milk-producing animal and its production levels. As many producers add water to dilute milk, determining the freezing point is a test for detecting such infractions.