Frost and Freeze

The words frost and freeze tend to be used interchangeably yet mean different things to meteorologists.  A frost by definition is a temperature between 33 and 36 degrees.  Because air temperatures are measured between 5 and 6 feet, when temperatures near 36 degrees or colder, temperatures near the surface are usually much colder, meaning some frost will be seen.  Plus, rooftops and cars radiate heat more rapidly and those surfaces may have frost as well.  A freeze by definition is when the actual air temperature at measured height drops to 32 degrees or colder.  Therefore, 36 degrees at the official height of measurement is often the point plant damage often begins.

Daryl Ritchison