Update: See comments. Whitehorse was closer to -7C to -8C colder than normal. Still top 3 in Canada for December 2012.
These are the 25 coldest stations (of the ones Environment Canada thinks are worth calculating anomalies for) in Canada for Dec 2012. The anomaly is calculated from the 1971-2000 normals.
13.2C colder than normal for Whitehorse Airport. Yukon data scraped from here.
Any mention in the news? You would think it would make the news wouldn’t you?
| Stn Name | Prov | Anomaly in C |
| WHITEHORSE A | YT | -13.2 |
| MAYO ROAD | YT | -8.6 |
| FORT ST JOHN A | BC | -8 |
| CHETWYND A | BC | -6.6 |
| GRANDE PRAIRIE A | ALTA | -6.6 |
| ATLIN | BC | -6.3 |
| WHITECOURT A | ALTA | -5.8 |
| PEACE RIVER A | ALTA | -5.7 |
| FORT SASKATCHEWAN | ALTA | -5.6 |
| CAMPSIE | ALTA | -5.5 |
| CRAIGMYLE | ALTA | -5.4 |
| CAMROSE | ALTA | -5 |
| TOFIELD NORTH | ALTA | -5 |
| EDMONTON WOODBEND | ALTA | -4.9 |
| GRAND RAPIDS HYDRO | MAN | -4.9 |
| SIMONETTE | ALTA | -4.7 |
| EDMONTON STONY PLAIN | ALTA | -4.6 |
| HAY RIVER A | NWT | -4.5 |
| DAKOTA WEST | ALTA | -4.3 |
| PLEASANT CAMP | BC | -3.9 |
| VEGREVILLE | ALTA | -3.9 |
| COWAN | MAN | -3.9 |
| FORESTBURG PLANT SITE | ALTA | -3.7 |
| LAST MOUNTAIN CS | SASK | -3.7 |
| KINDERSLEY A | SASK | -3.7 |
sunshine hours 
There was only two points taken for Whitehorse last month. Since these two days were particularly cold ones, you get a low average. In reality, Whitehorse was probably about 8 degrees below normal for the month.
Thanks.
I notice Weather Undergound has data for the whole month.
http://www.wunderground.com/history/station/71964/2012/12/22/MonthlyHistory.html
Average Temperate -22C.
About 7C colder than the 1971-2000 Normals.