This will be a bit shorter than some of the other monthly recaps because later this week we will be doing the 2018 Year-in-Review, and a lot of the big stuff will be covered there instead.
High Temperatures
Here we have the High temperatures for December 2018, and it was pretty mild and pleasant, but it was not anything extraordinary. We didn't come close to any records, although on a few days we were up near the warmest-since-1996 range.
Believe it or not, in December on-average we have 10 days with Highs above freezing. And for this mild and pleasant year we had...9. In comparison last December had 17 Highs above freezing, and 2011 had 19. So this wasn't a hot December, but it had more warm days than years like 2012 with 3, or 2009 with 0.
Our average High of -2°C was warm, but it was below 2011, 2006, 2005, 2002 & 1999. The two warmest recent Decembers were 2011 with an average High of 1.4°C, and 1999 at 2.1°C.
Notable this December was the lack of deepfreezes. We didn't have any Highs of -20°C, or -15°C, or even -10°C. The other time that had happened recently was in 2011. On-average in December we get 4 Highs below -15°C and 10 below -10°C.
Low Temperatures
And the Lows were fairly similar to the Highs, with most of the month above the average, although not extraordinarily so. The one particularly warm night was December 21st at -4.4°C, which was the warmest Low for December 21st since 1996.
The average Low this December was -11°C, which is on the warm side of things, and was just a little bit warmer than last year at -11.5°C. But it was cooler than recent years 2011, 2006, 2005, 2002 and 1999.
So it wasn't a particularly hot December, but the big thing was the we didn't have any real deepfreezes. On-average in December we get 13 Lows of -15°C including 6 Lows of -20°C. This year we only had the single -20°C on December 30th, which was pretty late, and which we took a detailed look at in First -20°C of the Winter of 2018-2019.
Coldsnaps
This chart is from First -20°C of the Winter of 2018-2019, and it's worth taking another look.
The winter of 2015-2016 was a big El Niño year, and by the end of December it had only had 2 Lows of -20°C. 2011-2012 had had 3 -20°C Lows by this point, and then the rest of these recent years had all had a week or two of cold Lows.
And so far this winter we have only had the 1 Low of -20°C.
Warm & Cold Decembers
When we add up the Highs & Lows the average temperature for this December was -6.5°C, which made it the 33rd warmest December since 1880. In terms of Highs it was the 31st warmest, and for Lows it was the 35th.
So this was an above average December, but it was not particularly unusual. In recent years 2011 was notable as the 4th warmest December, with an average temperature of -4°C; 1999 was the 2nd warmest at -2.5°C; and 1997 was the 1st warmest at -2.4°C.
The dotted red lines in this chart show the 10-Year average Highs, Lows, and Means for December. In The Months through the Years we saw that Edmonton's temperatures during December have warmed up a little bit over the years, but not as much as months like January and February.
Precipitation
We will talk about overall precipitation more in the year-in-review, but this December the International recorded 29mm of total precipitation (snow & rain) compared to 24.8mm at Blatchford. That is a little High for December, but it's not extreme.
Last December was a very low-precipitation month, with only 3mm at the International.
December Rain
We talked about this a few weeks ago in December Rain, but this year the International did record 2.6mm or rain on December 10th. The last time we had more rain in December was 1989 with 4.4mm.
Snow
The way that Environment Canada measures Snow/Rain/Precipitation can be a little confusing, because this month the International only had 29mm of total Precipitation, but that included 31cm of Snow. Normally it's more like 1cm of snow = 1mm of Precipitation, but I guess the snow this month was extra fluffy.
31cm of Snow is above average for December, but it's still below a recent year like 2009. It's also well above the 3cm that we had last December.
Snowdepth
In this chart we are checking in on snowdepth at the International.
On December 31st we were at 22cm, which is about double where 2014-2015 through 2017-2018 were at this time of year. It's about tied with years like 2012-2013, 2008-2009 & 2006-2007. And recently 2013-2014 was way up above 40cm at this point of the winter.
January Temperatures
In January on-average we get 11 days above freezing. Since 2000 there have been some low years like 2005 with 5, but there are other years that have lots of "warm" days like 2001 with 25, 2012 with 17 and 2014 with 16.
January is also our biggest month for deepfreezes, though. We average 8 Lows of -20°C or colder, and 3 of -25°C.
And that's it for the December 2018 Review. In the next week we will be back with the full 2018 Year-in-Review.
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