Frost temperature generally refers to the air temperature at or below the freezing point of water, which is 0°C (32°F). Frost occurs when the air temperature falls below this freezing point, typically measured about 1.2 meters above the ground

. More specifically, frost is the formation of a thin layer of ice crystals on surfaces, which happens when water vapor in the air deposits directly onto surfaces that are at or below freezing temperature without first becoming liquid water. This process is called deposition, and the temperature at which frost forms depends on the dew point relative to freezing-when the surface temperature falls below the frost point (the temperature at which air is saturated with respect to ice), frost crystals develop

. It is important to note that frost can form even if the air temperature is slightly above freezing, because the ground or surface can lose heat through radiation and become colder than the air, allowing frost to form on surfaces like grass or car windshields

. Conversely, freezing air temperatures do not always guarantee frost formation if there is insufficient moisture or other conditions are not met. In summary:

• Frost temperature is typically at or below 0°C (32°F), the freezing point of water

• Frost forms when water vapor deposits as ice crystals on surfaces at or below the frost point, which depends on humidity and surface cooling

• Frost can occur even if air temperature is slightly above freezing due to radiative cooling of surfaces

Thus, frost temperature is closely linked to the freezing point of water but also depends on local conditions like humidity and surface temperature.