Question: What is the difference between a frost and a freeze?
Answer: A frost refers to the conditions that allow a layer of ice crystals to form when water vapor condenses and freezes without first becoming dew. Frost may happen when the “surface” air temperature (officially measured at 4 or so feet above ground) is below 36 degrees F. (Ground temperature, meanwhile, may be below 32 degrees F, and below frost point.) Various factors must be present, such as clear skies, moisture, and calm or light winds.
A freeze can happen when the surface air temperature falls to 32 degrees F or below; frost may or may not form. A light freeze (between 32 and 29 degrees F) can kill tender plants. A moderate freeze (between 28 and 25 degrees F), sometimes called a hard freeze, can cause wide destruction to most plants. A severe freeze (24 degrees F and below), sometimes called a killing freeze, causes heavy damage to most plants. Many plants can survive a brief frost, but very few can survive a severe freeze.