The metric unit is degrees Celsius and the SI fundamental unit is the Kelvin. The degree Celsius, which is 1/100 of the difference between the freezing point and boiling point of pure water at sea level.Each °C equals 1.8 °F (Fahrenheit). The metric unit for temperature is the degree Kelvin.elsius or Kelvin The metric unit for temperature is the Kelvin (symbol: K), which is defined as 1/273.16 of the temperature difference between absolute zero and the triple p … oint of water.