Summer 2025 Postmortem

Mean 500 mb geopotential height July, 2025

It's been a long and abnormally dry summer across Utah and the West. There have been a number of light wildfire smoke days, but nothing like the fire and brimstone smoke season of 2021. The monsoon was largely MIA in Utah this year due to an unfavorable pattern (right figure). If you compare the average pattern this summer to different monsoon regimes, you can see that the summer 2025 upper levels match most closely to analog years where conditions are more favorable for the monsoon to focus over eastern areas of the Desert Southwest (figure below/top).

Typically, we want to see the broad Four Corners high establish itself and a heat low form over the Mohave Desert to facilitate moisture transport northward from the Sea of Cortez/Baja area into Utah (figure below/bottom). In general, this setup did not develop favorably for a good Utah monsoon year. Some could argue other regions of the west, including NM and far southeastern areas of AZ, got a decent monsoon but in large it was meager pickings across the west.

Less ideal 500 mb height pattern for a good Utah monsoon

More ideal July 500 mb height pattern for a good Utah monsoon

Depending on which angle you view it from, records were set in Salt Lake City for having nearly the driest summer season on the books. June-mid August only totaled 0.36" of rainfall at KSLC when on average those month receive a combined 1.44". We had some weak monsoonal pushes in late August that brought three days of measurable rainfall totaling 0.76" for the month, which is surprisingly above the monthly normal of 0.58". Unfortunately though, Salt Lake Valley is still about 5" liquid below where we should this time of year, sitting at an accumulated 10.35" for the year. To put it in perspective, SLC gets about 16" of water a year, so 5" is nearly a third of the normal yearly precipitation.

The water year ends at the end of September, meaning there is no real chance for recovering 5" of liquid to come out near normal. If you look at the chart to below, the whitespace between the black and blue line represents the difference between observed precip and normal precip. The whitespace gap has grown substantially over the past few months. For a bit of reference, SLC had a accumulated a little over 16" for the water year at this time last year. In summary, 2025 has been a dry summer.

PRISM temp anomalies Jun-Aug 2025

While temperatures weren't exceptionally hot this summer, compared to the past few summers, the average high temperature for June-August 2025 was 91.8 F. The normal average high for June-August is 90 F, so contrary to anecdotal feelings of how hot or not hot this summer was, this summer was in fact warmer than normal. A total of seven days of temperatures >= 100 F were observed in Salt Lake City. It's always nice to know how these numbers fit into the broader picture, so for comparison the summer of 2024 saw 20 day >= 100 F and had an average temperature of 93.3 F. However, 2024 summer was wetter. 

I have heard many water cooler conversations mention that the 2025 summer was "not that hot", however, I think this exhibits how weather and temperature can be highly relative and subjective. In a large part, we have gotten used to extreme heat as the new norm and therefore when people don't experience that extreme heat they qualify conditions as cooler when in fact conditions are still abnormally warm. The table below outlines some simple stats characterizing this past summer. In simplistic terms, it was a significantly dry and slightly hotter than normal summer. 

I can't extrapolate how others "feel" about this summer, but for me the heat was mostly bearable but the addition of the extreme drought really exacerbated the unpleasantness. If I had to rank this summer out of 10, I would give it a 5.5. Below I have shown my rankings for the past six summers. I mainly take into account temperature, number of wildfire smoke days, and amount of precipitation in my ranking logic. Being originally from the east, I appreciate a certain amount of rainfall and cloud cover. Now that the summer is finished, all I can hope for is a nice transition into fall, with a mix of some wet day and bright, clear, and mild days.