July 26, 2023 – With temperatures soaring past 110 °F in the Salt River Valley the past month, it has been too hot to do any exploring. I felt it was wiser to work indoors on the stack of research materials that are piling up in my office and wait for cooler weather.
And then I remembered some turn of the 20th century literature that was published extolling the virtues of the valley’s climate. The propaganda machine was in high gear when Dr. William Lawrence Woodruff, a Phoenix physician, claimed in 1898 the Salt River Valley had the best climate in the world and was equal to the Pacific tropics in all ways and even better because it lacked humidity.
Woodruff’s comments were echoed ten years later by J.W. Crenshaw, Commissioner of Immigration for Maricopa County, when he stated the climate was “warm” from June to September and the absence of humidity meant a temperature of 90 °F to 95 °F in the eastern states was worse than the highest temperature in the Salt River Valley.
Let’s examine these claims.
Table 1 below shows the heat index of four cities across the United States as recorded on June 21, 2023, the summer solstice. The heat index is what the temperature feels like to the human body when relative humidity is combined with the air temperature. The table clearly shows that even with its low humidity, Phoenix felt 10 to 20 degrees hotter than the other cities.
| Table 1: Heat Indices June 21, 2023 (summer solstice) | ||||
| City | Air Temperature (°F) | Relative Humidity (%) | Heat Index (°F) | Difference to Phoenix (°F) |
| New York, NY | 67 | 59 | 66 | -27 |
| Nashville, TN | 80 | 66 | 82 | -11 |
| Phoenix, AZ | 99 | 9 | 93 | 0 |
| San Diego, CA | 71 | 57 | 70 | -23 |
Table 2 below shows the same four cities one month later as the U.S. struggled through one of its longest and hottest summers on record. As you can see in the table, despite very low humidity, Phoenix felt even hotter (20 to 30 degrees hotter) than a month earlier compared to the others.
| Table 2: Heat Indices July 21, 2023 | ||||
| City | Air Temperature (°F) | Relative Humidity (%) | Heat Index (°F) | Difference to Phoenix (°F) |
| New York, NY | 87 | 43 | 87 | -24 |
| Nashville, TN | 89 | 50 | 93 | -18 |
| Phoenix, AZ | 115 | 11 | 111 | 0 |
| San Diego, CA | 75 | 64 | 75 | -36 |
The truth is the summer climate in the Salt River Valley has always felt much hotter than other parts of the country, even allowing for its low humidity. Early settlers encouraged by the propaganda of the likes of Woodruff and Crenshaw were likely shocked to learn the truth upon arriving in the valley: the gentry escaped to cooler climes to the north, leaving the masses to make do as best they could.
And making do often meant moving beds and stoves outdoors to escape the stifling heat of their wooden shacks, common construction for early settlers who put their cash into land and farming equipment, not housing. Of course, some residents did have adobe houses, which provided much more protection against the heat than plain wooden walls.
The people of the Hohokam culture (450 CE to 1450 CE) understood this difference quite well and in later periods built their houses with rammed earth walls six-feet wide at the foundation and tapering to two-feet wide at the top, superior to even a standard adobe house. See the post of May 18, 2023, showing pictures of the walls at Pueblo Grande (S’edav Va’aki). Certainly, these earthen construction materials and techniques were widely available to later Anglo settlers, too, so it is surprising more didn’t make use of them.