Monday, December 15 was unseasonably cold day across the region. Most locations had highs below zero. While subzero highs are not unusual in the northern plains, it is somewhat rare to have such cold temperatures in December. Below reviews the last time subzero highs occurred in Sioux Falls, Sioux City, and Huron and also the last time this occurred in December.
| Location | High on Dec. 15 | Date of last subzero high temperature | Date of last December subzero high temperature |
| Huron |
-5 |
February 3, 2007 (-2) | December 24, 2000 (-6) |
| Sioux Falls |
-4 |
February 3, 2007 (-3) | December 26, 1996 (-2) |
| Sioux City |
0 |
January 30, 2004 (-4) | December 26, 1996 (-1) |