AGCI Insight

Are we cool enough? A look at January’s temperatures

February 9, 2017

Here in the Roaring Fork Valley, 2017 launched with what felt like an unseasonably warm start. In the picture above, a mid-January site visit to Spring Valley revealed 16 inches of snow on the ground, but the balmy air got us thinking. A cold snap followed shortly after. Today with Basalt temperatures in the upper 50’s it feels like almost spring again. Curious to find out if we just perceived this weather as unusual or if the numbers actually backed up our perceptions, we turned to the data.

A look at annual average temperatures from Aspen Weather Station 372 (data available through the NCDC ) shows a slight upward trend in Aspen temperatures since from 1980-2015. Archival data from December of 2016 was not yet available, so we left 2016 out of the graph. But what about just the seasonal temperatures for winter?

Looking at the same weather station (Aspen 372), we updated a graph from the 2014 Climate Change and Aspen Report. This graph shows averages by decade of winter temperatures from December through February (DJF). The blue bars show a 10 year average (for example 1940-1949) and the green bar shows this decade so far (2010-2016). It’s important to note that the station moved to a slightly higher elevation in 1980. Average daily DJF temperatures since 1940 have increased since the 1970s but are a bit lower this decade than they were the previous decade. When you look at averages of minimum daily temperatures, however, a trend of increasing temperatures appears.

Although these graphs offer some insight into temperature trends in general, they still didn’t answer our question about January. How did it compare to the last few years? This time we looked at our own data, the data from the iRON stations. We graphed daily temperatures just for the month of January for every year since the stations were installed.

At Brush Creek January 2017 temperatures (in dark blue) were quite variable, with a very cold day on the 6th. Overall, however, sometimes they were lower and sometimes they were higher than January temperatures for the same date on 2014, 2015, or 2016. Further Down Valley, the graphs looked different. At Glassier Ranch , located near Basalt, average daily temperatures for 2017 (in dark blue again) sat pretty consistently above January temperatures for 2014, 2015, or 2016. The exception, of course, was that cold, cold day on the 6th.