If you're thinking that this has been one cold January, you are absolutely right. Through the first 21 days of 2009, the temperature has averaged 4.4 degrees below normal. Fourteen of the 21 days have had daily average temperatures colder than normal, and we are 10 percent above the normal heating degree day (HDD) total for the month so far. For those unfamiliar, a HDD is a measurement of heating fuel usage. It is calculated by subtracting the daily average temperature--(MAX + MIN) /2--from a base of 65 (the average temperature below which it is assumed that you must use fuel to heat your home). So, for example, a day that has an average temperature of 25 degrees, accumulated 40 HDD (65-25). The more HDD we accumulate, the more fuel we use (i.e., the colder it is).
Normally, at this time of January, we'd be anticipating a "January Thaw." This phenomenon, a marked warming late in the month that lasts a few days, actually shows up in long-term averages for the region. But don't look for one this month. Computer models show a quick warm-up (to the upper 30's) for Friday, but then right back to the below-normal weather pattern for the remainder of the month. The daylight hours are getting longer now, but the old saying still holds true--"As the day lengthens, the cold strengthens." In fact, the climatologically coldest days of winter come at the very end of January and into the first few days of February (in spite of the increased daylight). Things normally begin to turn around by mid-February, but don't fool yourselves--there's still plenty of winter left before the grass begins to turn green once again. Stay warm.
