Annual Temperatures in Aspen Increasing by 0.0061 °C per year on Average Since 1980

10/1/25

Link to my complete analysis and Python code

Introduction
Aspen Colorado is a popular destination for winter sports, known for its pristine powder which is great for skiing and snowboarding. Since the economy of Aspen is so dependent on low winter temperatures and good snow conditions, I wanted to determine if there have been any trends in Aspen’s climate over the last several decades.

Photo credit: https://commons.wikimedia.org/wiki/User:Rhododendrites
To research this, I searched for weather station data in Aspen available from the Global Historical Climatology Network daily (GHCNd), provided by NOAA’s National Centers for Environmental Information (NCEI). I used station ASPEN 1 SW, CO US, which has 99% daily temperature summary data coverage from 1980 to present. According to NASA, a 30 year timespan is required to observe any meaningful change in climate, while timespans less than this simply show variability in weather patterns. The station I chose has a 45 year timespan of consistent data coverage, meaning that this timespan is long enough to observe meaningful changes in climate.

The raw data has daily average temperatures, and I wanted annual average temperature values to understand longer term changes in climate. In Python, I calculated the annual mean values and resampled to one temperature value per year. Next, I used the sklearn library to fit a trendline to the data using the Linear Ordinary Least Squares (OLS) Regression method.

This graph shows an increase in average annual temperature in Aspen, CO of 0.0061 °C per year since 1980. Over 45 years, this is a total increase of 0.2745 °C.