Publication Date May 29, 2017

U.S. Daily Record Highs Outnumber Lows 5 to 1 since 2010

United States
Galveston, TX, one of the oldest cities on the Texas coast. In April, meteorologist and blogger Matt Lanza posted an article on Space City Weather about the unusual streak of record warm temperatures observed in Galveston since 2010 and especially over the past year. From 2010 through April 2017, Galveston tied or set 216 daily record highs or record high minimums out of a possible 732. Photo:  PhilFree, Wikimedia Commons

As detailed in the caption above, Galveston, Texas, has set an amazing number of heat records in the last few years. Blogger Matt Lanza (@mattlanza) recently wondered if any other city in the U.S. has broken so many heat records in the same span of time (since 2010). I decided to follow that line of inquiry and researched 60 cities in the contiguous U.S. that have National Weather Service NOWData online records going back to at least 1895. In addition, I looked at six sites in Alaska and Hawaii as well, although only two (Juneau and Honolulu) have periods of record (PORs) dating back to 1895.

I chose the 60 towns and cities based on their geographic distribution (more or less evenly spread across all geographic regions of the U.S.) and also for their periods of temperature record going back to at least 1895 in the NOWData files. I also made a point of including some small towns in significant geographical locations such as Cape Hatteras, North Carolina, and Glasgow, Montana, thus minimizing the influence over time from urban heat islands (see below).

For the 66 sites (60 in the contiguous U.S., plus six in Hawaii and Alaska), a total of around 96,000 data points (66 sites x 366 days x 4 parameters) were perused. I then manually counted how many of the daily temperature records (out of a possible 1464 for each site--366 days x 4 parameters) were recorded from January 2010 through April 2017. I’m sure I may have missed a few records here and there, given that there was no way for me to make the counts in an automated fashion. Nevertheless, the trends in the results remain obvious.