The past several Decembers have been cold and snowy.
On average, Sioux Falls sees 8.2 inches in December, but the last four years the month has averaged close to 17.5 inches. The heaviest falling in 2009 with a total of 27.8 inches of snow.
We might be able to buck that trend this year as it looks like the jet stream will stay well to our north this month. This means warmer than average temperatures and fewer chances of precipitation.
We're just coming out of a record dry autumn. The last time we were this dry was in 1952, that following December gave Sioux Falls below average snowfall with 3.7 inches. Temperatures were warmer than normal that month with an average high of 32. The warmest high was 51, and the low dipped down to nine below. Don't be surprised to see the same temperature swing this December.