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  • Writer's pictureJosh Kurz

Does Early September Seem Hotter Than Normal?

Updated: Apr 25, 2020

That's the question I pondered during the 1st week of September as I sweat through my afternoon science lessons. Our mountain high school doesn't have air conditioning and the thermometer in my upper-level classroom topped 85 degrees! I was pretty sure that we were breaking temperature records, but I wanted confirmation from the historical records.

A massive snowfield persists at the headwaters of the Navajo River: 9/1/19

Since I'm used to accessing data from SNOTEL stations (and federal temperature monitoring in Pagosa Springs ceased in 1998), I downloaded the maximum temperature records from the Wolf Creek Summit SNOTEL located at 11,000 feet near the top of Wolf Creek Pass. Unfortunately, the period of record is relatively short since the daily temperature wasn't measured consistently until 1987. Also, the data set has a few holes due to temperature sensor failure (2003 and 2013 are missing large portions of summer data), but it's good enough to answer my initial question with reasonable certainty.

After tediously condensing 12,000 temperature measurements into a plot-able form, I was able to answer my initial question and as well as find out more information about maximum temperatures than I had originally intended. Between August 25 and September 5th, the maximum temperature on Wolf Creek Pass climbed to at least 70 degrees 12 days in a row and broke or tied 11 maximum temperature records! The area averaged 11 degrees above normal during those 12 days! On September 2nd and 3rd, the temperature reached 73 degrees, which is the same days we were sweltering in my classroom. Since 1987, the September temperatures have only reached or exceeded 70 degrees on six occasions: 4 days in a row in 1995, 1 day in 2002, and 1 day in 2017. So 70 degrees on Wolf Creek Pass in late August and early September is not unprecedented, but 11 days in a row is.

When the blue line exceeded the red line, a new record temperature was set.

I also learned that the highest temperature recorded during the period of record was 82 degrees on July 5, 1989. And by taking this analysis further, I was able to plot the maximum temperature records by month and determine the year in which they occurred. As you can see, 2019 holds the new record for September. I found out that the temperature can climb above 50 degrees during any of the winter months. Lastly, 9 out of the 12 monthly records were set in 2002 or later.

One question that came to mind is how the beetle kill has influenced the temperature values. I assume there is less shade and less humidity without the mature trees, but that's a another study for some graduate student. Nonetheless, my hunch was right and early September was definitely hotter than normal and one for the record books!

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