Thursday, June 17, 2021

If June Is the New July, What Will July Be?


This blog post is brought to you by Panda Express, which along with the adjoining but depleted Union food court, appears to be the only place to eat on the University of Utah campus and provided me with the fortune above yesterday.  

Forget that.  

This June has been awful.  How awful?  Some statistics:

  • Although we just went through the climatologically coolest first half of June, if the month ended today, it would still rate as the warmest on record at the Salt Lake City International Airport (KSLC) by 1.4˚F.  
  • Likewise for Tooele.  So far 1.1˚F hotter than the hottest June on record (records back to 1896).
  • The average temperature at KSLC for June 1-16, 78.9˚F would rank in the top 25% hottest Julys.  More on July in a minute.
  • KSLC has had no measurable rain so far this month (they recorded a trace on June 5).
But what about the future? 

As it says at the gates of hell, Abandon Hope All Ye Who Enter Here.  

The GFS forecast through June 27 below is very much July-like. The storm track remains to our north.  Weak troughing at times near the west coast.  Maybe a brush-by slight cool down.  

This isn't a recipe for another 107˚F day, but it also isn't a recipe for a return to near average temperatures.  Temperature forecasts from the National Weather Service's National Blend of Models show we will likely see high temperatures near or above 90 for the period.  The best odds for below 90˚F are on Sunday and Monday when we may feel the effects of the bush by.  Still the majority of NBM members call for highs at or above 90˚F those days.  

Source: NWS

I'm not a fan of looking farther out, but I'll give you what you want.  The Climate Prediction Center 8-14 day outlook, covering the last week of June, shoes the odds stacked for above average temperatures.  

Source: CPC

Essentially, this June is the new July, with a large-scale pattern, temperatures, and precipitation characteristics more reminiscent of that typically hot, dry month than June.  

But what will July bring?

Really, I have no idea.  However, we can look at past Julys and think about what the climatological likelihoods are, doing some tweaking and educated guesses since our climate is changing. 

July is on average our hottest month, but it also exhibits the least amount of variability from year to year.  The coldest July on record occurred in 1993.  That was a black swan July with an average temperature of 69.9˚F, considerably cooler than we've had so far this June.  


However, July 1993 had two things going for it that we don't have today.  First, the planet was cooler in general.  Second, Mount Pinatubo, a volcano in the Philippines, erupted in June 1991, spewing particulates into the stratosphere and temporarily cooling the planet about 0.5˚C through 1993.  A repeat of July 1993 is highly unlikely.  

Perhaps a reasonable request would be something like July 2015, which was the coldest July in the past 20 years.  The average temperature was 77.4˚F, slightly cooler than we've seen so far this June.  My blog post from July 23, 2015 (Perspectives on Our Fantastic July) suggests that the month was "fantastic with tolerable temperatures and the occasional showers and thunderstorms to help moisten things up."  

On the other hand, since 2000, there have only been two Julys with an average temperature lower than the 78.9˚F we've had so far this June, 2011 (78.5) and the aforementioned 2015.  This is a small sample size (20 years), but our July climate has shifted so much that it's unclear how useful pre-1990 temperatures are for present day climate.  

My view is that it is looking pretty likely that the average temperature from here until the end of July will be comparable to or higher than what we've seen so far this June.  The odds that it is lower are probably less than 20%, and the odds that it is much lower (say more than 2˚F) are probably less than 5%.  

How's that for positive perspective? 


  1. "It's unclear how useful pre-1990 temperatures are for present day climate."

    While there are resources for various climate averages under different emissions/warming scenarios, there's not much that I'm aware of regarding what extremes will be in store in the future. That's really what we need to design to, and that's not always happening. Solar PV, Wind, Combustion Turbines (whether natural gas or potentially H2 by 2030) all have reduced output in high temperatures, which also corresponds to highest electrical demand. You've mentioned needing to build for a 21st century climate in the past. Any tools for expected extremes would be very useful if you can provide them. I know the answer depends on emissions/warming going forward, but as we learned from California last summer and Texas this winter, there's a lot of work to do here, and these events are becoming more common. Any guidance or resources would be greatly appreciated.

    1. Here's a review article to get you started:

      Hopefully it is not paywalled. Specific answers for specific locations are challenging.

    2. My bad. That's an older article. Let me post something else eventually.

    3. Not quite as old...focused on southwest:

      If I think of something more recent and up to date, I will pass it along. There could be something in the most recent National Climate Assessment:

  2. Thank you very much Jim. I found this resource called Climate Explorer through the National Climate Assessment link which gives a county by county breakdown on future climate predictions based on high and low emissions variables:

    I'll undoubtedly have more questions related to this in the future as this is an important design consideration, but this is extremely helpful.

    In the meantime, in a nod to Panda Express and our positive perspective being the greatest asset, LBL released a report indicating that CO2 emissions from the power sector in 2020 were 50% lower than projected back in 2005 while overall electrical bills have also decreased:

    We should acknowledge the success that we have so far. It may not be a perfect situation today, but we also could have done a lot worse. I'd like to take a moment to acknowledge the fact that we've done a lot better than expected. Otherwise we lose that positive perspective, and we'll need that positive perspective because the next 50% reduction to zero emissions will be much harder.

  3. Two thoughts:
    1. The value of conservation and improved insulation is increasing each year.
    2. When, typically, is the hottest part of the year here in Utah. I know it varies across the country, and any given yearmay not be typical.
    Thanks for your perspective

    1. At KSLC, the hottest part of the year on average is late July. I think on average the hottest day of the year is about July 24 if I'm remembering right.

  4. I believe there is a new meteorological season; SummerX: from june 21 to aug 15. The second half of spring is summer. And summer again from aug 15 to sept 21.

  5. Unfortunately they aren't going to get half the coverage of our 107 record high last week, but overnight lows have been absolutely brutal this past week. It appears we tied the June record high overnight low yesterday at 78 degrees, and we have not dropped below 68 at KSLC for a week which appears to be unprecedented for June. Even that weak cold front couldn't get us below 70 last night (though we may have better luck tonight).

    Also, if one measures by average temperature, that 107 degree day last week came with a 75 degree low which ties for KSLC's second-hottest day ever at 91F. (The record in that department is 91.5F set on 7/15/2007, which had a 105 high and 78 low).