What temp does it start frosting?

It's impossible to answer "What temp does it start frosting?" without knowing what "it" refers to.

Here's why:

* Frosting is a process, not a specific substance. It happens when water vapor in the air condenses onto a cold surface.

* The temperature at which frosting occurs depends on the humidity. Higher humidity means frosting can occur at higher temperatures.

* Different surfaces have different freezing points. For example, water freezes at 32 degrees Fahrenheit (0 degrees Celsius), but other substances can freeze at different temperatures.

To get a helpful answer, please tell me:

* What specific surface are you asking about? (e.g., a window, a car windshield, a piece of fruit)

* What is the humidity level? (e.g., 50%, 70%)

Once I have this information, I can give you a more accurate answer.