Eleven months down, one to go: What kind of weather to expect in December (historically)
BOISE, Idaho (KBOI) —
We're about to shut the door on the month of November, leaving only one month left on the calendar in 2017: December.
So what's December all about (historically speaking)? What changes between November and December that makes the latter feel so much more 'winter-like'? (Aside from the season change itself)
November 2017: Warm and wet, (but no snow)
Let's start with a quick look back at the month of November. Overall, temperatures played nice. All but eight days, our temperatures were either at or above the average mark (which, during the month ranges from 56°-41°).
The calendar above breaks down which days were 'above average,' 'below average,' or 'average.' Especially the second half of the month, we experienced a mild stretch of weather. Overall, there were six days in the month of November where temperatures pushed into the 60's. Thanksgiving was a day for the record books, as our high temperature of 66° in Boise broke the record for warmest Thanksgiving (which falls on different days every year) and warmest temperature on that particular date in history (November 23).
It was also a relatively wet month. Close to two inches of rain fell at the Boise Airport in November (1.77"), which is well above our average precipitation for the month (1.35"). While we typically see 2.4" of snow in November, this year, that number was kept to 0.0" (which was probably a relief to some).
So what about December in general?
Historically, December is Boise's second snowiest month behind January. On average, seven inches of snow falls during the month of December (although often times not all at once like last year). Last December was a bit of an anomaly - the eighth snowiest on record, actually! (See below). The most snow to fall on a single day in December was 9.8" back on December 20, 1996.
Typically, we see about 1.55" of precipitation in the month of December.
As for high temperatures, the average value ranges from 41° at the beginning of the month to 36° at the end of the month. Lows tend to range between 23-27°, although there are obviously exceptions in both categories. Last year, the coldest temperature recorded in the month of December was 0° on December 18. The warmest daytime temperature was 45° (on both December 4 and December 5).
Other December extremes:
Those numbers are nothing compared to the records though. On December 22, 1990, the low temperature dropped to -25°. That's the coldest number on the temperature dial in Boise's history since 1900. Before that, in the 1880's, there were only three days that got colder (-26° (1888), -27° (1883), and -28° (1888). Fun fact: my parents apparently didn't mind the cold...they got married that day.
What to expect this December:
It's impossible to tell what the month as a whole will look like, but this article gives a good indication of what the long-range forecasts are suggesting for the next couple of weeks (which may not be great news for skiers and boarders).