December is starting off on nearly a record warm note as temperatures have climbed into the 60s, but how common are 60s this month? In Des Moines, 60s have been recorded in 45 of the past 143 years (when records for temperature began). That’s 31% of years. The Climate Prediction Center’s monthly outlook for temperature suggests that the trend of above average temperatures will continue. Though, that doesn’t mean temperatures will stay in the 60s.
Let’s look at what average is here in Des Moines…On December 1 the average high is 41°…that number falls to 32° by December 31. Likewise, on December 1 the average low is 24° and falls to 16° by December 31. That all averages out to 26° for December in Des Moines. In 2020, the average temperature was 29.3°, meaning Des Moines was 3.3° above average.
Back in 1889, Des Moines saw its warmest December ever recorded. The average temperature was a whopping 39.5°. That’s 13.5° above the average…and actually warmer than the average maximum temperature of 34°.
The coldest December wasn’t as long ago. In 1945 Des Moines saw an average temperature of 18.0°…that’s 8.0° below average for the month.
Last year (2020) the average temperature was 3.3° above average in Des Moines.
It’s been 21 years since Des Moines saw its snowiest December. In 2000, Des Moines recorded 30.3″ of snowfall which was 21.3″ above the average December snowfall of 9.0″. Two years later in 2002 Des Moines saw its only snowless December….that means there’s more than a 99% chance of seeing measurable snow this month. In 2020, Des Moines recorded 17.1″ of snowfall.
While Des Moines’ average snowfall is 9.0″, the average amount of liquid precipitation is 1.42″. Note: When snow falls it is melted down to give the liquid equivalent, so this number includes any snow that fell within the month.
The Climate Prediction Center’s outlook for precipitation is less concrete. There are equal chances of seeing both above average and below average precipitation across Iowa in December. While the next week looks mainly dry, the extended forecast does hint at a couple chances for measurable snowfall. The first chance for measurable snowfall in the extended forecast looks to be December 7th-8th.
Further details on snow chances will be provided over the next week as more information on the weather pattern becomes available.