Define “meteorological” winter as opposed to “regular” winter

Dear Tom,

I know the difference between “meteorological winter” and “regular winter,” but why do you seem to prefer meteorological winter?

Demetrius Villa,
Chicago

Dear Demetrius,

Let’s define those terms. Meteorological winter (in the Northern Hemisphere) is the period from Dec. 1 through Feb. 29, whereas regular winter is the period from approximately Dec. 21 through March 21. Both the beginning and ending dates of regular winter vary by a day or two, depending on the year. I prefer meteorological winter (and the other three seasons –spring (March through May), summer (June through Aug.) and fall (Sept. through Nov.)) because they are unvarying in their beginning and ending dates. This is essential in making comparisons between seasons (temperatures, for example) from one year to another. The data are always from identical periods of time.