WRAL WeatherCenter Blog

I was reading an article on Fruit Tree cultivation. The article mentioned the "mean" temperature. In this case, growth starts when the "mean" temperature is above 70 F. Is the "mean" temperature calculated using the high and low for the day?

Posted May 23, 2007 2:36 p.m. EDT

MIKE MOSS SAYS:     Carl,    I can't say for certain the exact interpretation of "mean" that may been applied in that publication, but you are probably on the right track. For example, each day the National Weather Service lists a daily average temperature for reporting locations, and that daily average value is computed by taking a simple mean using the sum of the low and high for the day divided by two. That value is commonly used in computing heating and cooling degree days, and in agriculture to compute "growing degree days." However, one could compute a more sophisticated mean by, for example, adding up every hourly temperature observation through the day and then dividing by 24, and so on. In most cases, this wouldn't be too far off from the value obtained through the simpler method, but there could be occasional situations in which the two would differ significantly.