This summer has been relatively mild, compared to some we have recently experienced.
In 2012 we recorded 39 days with a high temperature of 90 degrees or greater. This summer we have only had one such day so far — July 22, when the temperature was 93.
Tuesday is the 81st anniversary of the 127-degree high in 1933 at Greenland Ranch in Death Valley, California, that set the national record for the month of August. Such heat is of a completely different character than anything that has ever happened in and around Madison.
The all-time high for Madison was set on July 14, 1936, when the temperature soared to 107 degrees.
It is important to note that 107 here might be more uncomfortable than 127 in the desert, given that such a hot day in Madison is nearly always accompanied by very high humidity, while the desert is always very dry.
In fact, to get as hot as 127 degrees, even at Death Valley, special circumstances have to be met. Most importantly, there has to be a strong flow of air off of the surrounding higher terrain. This sinking air is compressed as it moves downward to higher pressures, and the compression leads to substantial warming. At the same time, this compressional warming lowers the relative humidity of the air, rendering it very dry as well.
Many of us experienced the extreme heat and humidity of July 13, 1995, when the temperature in Madison was 101 with a dew point of over 80 degrees – truly miserable. Still, the question of whether super hot and super dry is more uncomfortable than really hot and super humid is perhaps dependent on personal tolerance.
I think we can all be glad that we have not (yet) been put to that test this summer.