It's Not the Heat It's the Humidity

Yesterday's 108F high in Newark, New Jersey was even higher than Salt Lake's all time record high set on 13 July 2002 of 107F.  Remarkable.

Truly oppressive, however, is the combination of heat and humidity.  Let's do a quick comparison.  When Salt Lake hit 107, the dewpoint was about 40F and the relative humidity 10%.

That's a heat index of "only" 101F.

In contrast, when it hit 108F yesterday in Newark, the dewpoint was 69F and the relative humidity 29%.

 That works out to a heat index of 117F.  Unbearably uncomfortable, although I suspect there were locations with a higher heat index in the region.