How much wood … would a woodchuck chuck … no, we’re not doing that one. Instead, we’re going to talk about actual wood. As in, how much have you gone through this February, as compared to last February? I’ll bet your answer is, a lot more this February! And that is not surprising, given that the first 17 days of this month were the coldest of any February on record (courtesy NWS Caribou), and records at Caribou go back to 1939.
Now, one way of measuring how cold or warm things have been, compared to other months or years, is to use the rather oddly named “degree days.” In summer we use cooling degree days and in winter we use heating degree days. Great. What the heck is a degree day?
Essentially, degree days are a measure of energy usage, and here is how they are calculated: If the average daily temperature (high + low divided by 2) is above 65 degrees F, it is assumed you need to cool your home. If it is below 65, it is assumed you need to warm your home.
Here is an example of something we would see in winter: High of 20, Low of 0. Average for that day is 10.
Next, you simply subtract that day’s average temperature, (10) from 65. So, in this example, 65 – 10 = 55.
That day would be said to have had 55 heating degree days.
And, using that same “need to heat if average temp is below 65” concept, the higher the HDD value, the colder it has been, and the more energy you have used.
There are many ways degree days can be used. Here’s one of them. Let’s say you are moving from Caribou to Boston, and you’re going to need to heat roughly the same amount of living space. Well, you can expect to use approximately half as much fuel. How could you know this? Because Caribou has an annual average of about 9,500 heating degree days (HDD), while Boston averages about 5,000.
Let’s close things up by coming full circle, back to cold months. There is only one month on record where over 2,000 HDDs were amassed at Caribou, and that was the brutally cold January of 1994, which also happens to be the only month on record where the average temperature for the entire month was below 0 degrees Fahrenheit!
Ted Shapiro holds the Broadcast Seal of Approval from both the American Meteorological Society and the National Weather Association. An Alexandria, Va. native, he has been Chief Meteorologist at WAGM-TV since 2006. Email him at tshapiro@wagmtv.com.
