On Dec. 16, 2009, CWG’s morning forecasts began assigning a number on a 0-10 scale to describe our local weather. Sure, temperature and precipitation details come first and foremost, but why not also sum up D.C.’s daily weather in a single number? A sunny day in the 70s gets high marks, while a rainy day in the 30s is mediocre at best.

Average daily digit for each meteorological season since it was first introduced in Dec. 2009. (Justin Grieser)

Of course, like many things in life, nice weather is in the eyes of the beholder. So, if a balmy winter day isn’t your thing, you’ll disagree when our forecasters give it an 8 out of 10. Likewise winter enthusiasts (myself included) are disappointed when a cold day of brilliant sunshine earns low marks. Only during those blissful spring and fall days around 75 degrees do most people agree that D.C.’s weather is just right.

During winter and summer in particular, we hear a lot of debate about the daily digit. Some prefer year-round warmth. Others like a good dose of Old Man Winter and suggest CWG’s forecasters are biased toward warmer temperatures.

The third anniversary of the daily digit gives us a chance to see where it stands…

(Justin Grieser)

In the past three years, CWG’s forecasters have assigned 1,092 daily digits. Overall, the digit has averaged 6.1 out of 10, up slightly since our 2011 report. In 2012 (to date), D.C.’s weather has earned a 6.4 average on the scale.

The most frequent daily digit is a lucky 7 out of 10, given to 17.3 percent of all days. Sixes and fives are not far behind. Increasingly, there’s been a bit of grade inflation, with eights now assigned more frequently than fours.

The opening graph shows that seasonally, spring and fall still earn the highest grades (averaging at least 6.5 out of 10), while summer and winter get lower marks. If there is any evidence of CWG’s warm bias, just look to the warm winter of 2011-2012, when the daily digit averaged a high 6.3 – well above the two previous winters!

CWG forecasters are fairly consistent over time in their choice of daily digits. As we found last year, the highest digits coincide when DC sees high temperatures anywhere from 66-85 degrees. (Justin Grieser)

On the other hand, those who think CWG grades cooler weather too favorably may also have a point. Since last year, our forecasters now give slightly higher scores to days with high temperatures ranging from 56-65 compared with days in the 86-95 degree category (maybe CWG forecasters grew weary of our recent record-hot summers?)

There are endless ways to parse this, but for now I won’t delve any further. After all, the daily digit offers a quick, unscientific snapshot of D.C. weather and should never be taken too seriously. But for all the discussion it generates, its 3rd birthday is certainly worth a mention!

What’s your take on CWG’s Daily Digit? Is it helpful, fun, or too biased? Feel free to comment below…


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