Wednesday, May 31, 2023

A Remarkably Warm May

In the previous post, I commented about the Goldilocks temperatures over the past two weeks.  In my view, they were ideal for avoiding the use of home heating or cooling.  

That said, they were not Goldilocks from a climate perspective. In fact, this May is going to go down as the warmest on record at Salt Lake City.  With one day left to go (today), the average temperature for the month is an incredible 67.1˚F.  That eclipses the prior record set in 1934 of 66.7˚F.  


The 67.1˚F will likely go up a bit more today.

I actually found this a bit surprising because there hasn't been any exceptional heat.  However, May has been characterized by relatively little variability in large-scale weather systems compared to normal.  Instead we've simply had sustained warmth.  In the plot below, the range of "normal" (i.e., averages for 1991–2020) is indicated by the green background.  This May, we had only 5 days with a maximum temperature below average and only 4 days with a minimum temperature below average.  

Source: NWSFO

Since I always get questions about the veracity of the airport temperatures, below is a graph of the monthly mean temperatures at Bountiful Bench, with continuous records back to 1975.  With one day left to go, this May rates as the 2nd warmest (63.6˚F) behind only 1992 (63.9˚F).  


We will probably end up just behind 1992 at that location (by about 0.1˚F) based on last night's minimum and the forecast high for today.  


  1. Any thoughts on rain at KSLC. This year is 0.52 inches compared to normal 1.82 inches. My sense is lack of rain contributed to warmer temps, though as you say its been a Goldilocks month of mild not hot not cold.

  2. Definitely a warm month no doubt! Do you have any data on Ogden and/or Provo? Once again the Salt Lake City airport is setting warm records at a much faster pace in recent years compared to other cities like Ogden and Provo. As you have noted in the past the official observation site was located in downtown Salt Lake City until 1928 before being moved to the airport. The airport location was then moved in 2011 to a different airport location. The current airport location has undergone significant changes in ground cover since it was installed. The current site was originally a grassy/weedy area with less pavement/buildings around, the observation site is now surrounded by dirt/gravel with more buildings/pavement encroaching the site. These factors obviously increase temperatures especially on sunny light wind days.

  3. Exactly the warming is pretty much all artificial and due to urban heat island / thermometer sitting issues.

  4. Seemed like one of the best recent Mays up on the east bench!