Temperature Continuity Study at the Historic Fort Collins, CO Weather Station

Weather observations have taken place at the Fort Collins, Colorado State University campus station (05-3005) continuously since 1889. 2013 marks 125 years of observing at this station, which is one of the longest climate records in Colorado. The primary observed variables include: temperature, precipitation, snowfall, snow depth and evaporation, however many other elements are unofficially collected from an automated station. The station maintains both a Hazen shelter with liquid in glass thermometers as well as an MMTS (maximum/minimum temperature system). These instruments provide redundancy in case of instrument failure and observer error, however liquid in glass observations have remained the primary observing equipment for temperature for the duration of the station. This allows the temperature time series to be free of biases that became apparent with the MMTS transition. However, in 2002 a transit center bus terminal was constructed just to the south of the weather station to accommodate the growing campus and surrounding community. This study investigated the effect of that construction on temperatures reported from this station by comparing it to nearby COOP Fort Collins 4E (05-3006) and a local agricultural weather station Fort Collins 01 (FTC01) both of which are in more rural settings than campus which continues to expand. While the campus station shows a marked upward trend in temperatures over time, this is due to the urban heat island. Detectable difference in summertime maximum temperatures was 0.3 F when compared to the other stations. All stations saw increases in the frequency of 95 degrees and higher temperatures since transit center construction in 2002.