But exactly how hot is it, and how do we know?
"Official observations for Phoenix are taken at Sky Harbor Airport with our automated surface observing station,” said Paul Iniguez, a meteorologist with the National Weather Service.
He said there are stations all over Phoenix that measured temps ranging from 107 to 124 degrees Tuesday.
The official, daily record-breaking high was 119 degrees for Phoenix.
Temperature records started in downtown Phoenix in 1895. The observation moved to the airport in 1953 with only small adjustments since then with updated technology.
"1994 is when our automated equipment went in,” said Iniguez, “and then the automated equipment was relocated in 2000 to its current location."
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Are we able to know for sure that 122 was our all-time high temperature since the technology has changed from mercury to digital over time?
Iniguez said yes, because "there's going to be very subtle changes, but all the instrumentation is calibrated and has a certain threshold that it need to meet to be accurate."
These are standards the other observation stations may not meet, because they may be in the sun or on a metal roof, for example.
Iniguez said “to compare apples to apples,” consistency and accuracy is the National Weather Service’s goal by monitoring the heat at Sky Harbor all day for more than a century.