US July maximum temperatures have plummeted since the 1930s.
Over the same period, US July minimum temperatures have increased.
The difference between maximum and minimum temperatures has dropped by more than 15%.
This is very indicative of urban heat island contamination. Paved roads, snow removal, irrigation, and other factors cause nighttime temperatures to be elevated, and all have increased sharply since 1930. We have seen nearly 2C (3.6F) summer UHI since 1930.
So how much does USHCN correct for UHI? less than 0.1F
NOAA has documented more than six degrees of UHI in Phoenix.
At the same time they exaggerate TOBS and FILNET, USHCN massively undercounts UHI. If they did their adjustments properly, they would increase the cooling trend since the 1930s, rather than reverse it.
As a result of data tampering, they have made a complete mockery of the US temperature record.
Zeke blows this all off as “changing station composition” This is not credible for many reasons. Zeke needs to come up with a physical explanation for why the changes since 1930 have caused daytime temperatures to plummet, while nighttime temperatures have increased. And remember that the station loss didn’t begin until 1990.