how cold does it have to be to frost
Frost or freezing occurs when the temperature of air falls below the freezing point of water (0 Â°C, 32 Â°F, 273.15 K). This is usually measured at the height of 1.2 m above the ground surface. There is a rather subjective scale to show several degrees of frost severity: 1  slight frost: 0 to â3.5 Â°C (32.0 to 25.7 Â°F).