Are the temperatures used in degrees Celsius or Fahrenheit?
• OMAFRA uses the Canadian degrees Celsius standard for temperatures while the United States uses the degrees Fahrenheit scale. Another problem that has caused some confusion over the years is with the terminology used. Here in Ontario we use the terms Growing Degree Days (GDD) and Crop Heat Units (CHU), which represent two different, temperature dependent, development models. The Crop Heat Units calculation now used in Ontario is identical to the traditional Corn Heat Units calculation with the name change reflecting its now broader application to other crops. OMAFRA has developed a CHU Factsheet with a full description of the CHU calculation and it’s applications. Growing Degree Days are some times referred to just as Degree Days or Degree Days Averaging Method. Some jurisdictions also use the term Heat Units interchangeably with Degree Days.
