. Author manuscript; available in PMC: 2017 Sep 5.

Published in final edited form as: Bull Am Meteorol Soc. 2016 Nov 22;97(10):1817–1830. doi: 10.1175/BAMS-D-15-00181.1

Table I. Core variables used in EHE definitions. Capital X's indicate definitions used in this analysis; boldface X's with asterisks indicate definitions published in the literature.

Daily heat metric	Duration (days)	Intensity
		Relative threshold							Climate-normal-based threshold		Absolute threshold
		P80	P85	P90	P95	P81/P97.5	P98	P99	Mean + one std dev	Mean + two std dev	90°F	95°F	100°F	105°F
Daily max temp (T_max)	≥2			X*	X*		X*	X*	X	X	X	X*	X*	X*
	≥3		X*	X	X		X*	X*	X*	X*	X	X	X	X
	≥4		X	X	X		X*	X*	X	X	X	X	X	X
Daily avg temp (T_av)	≥2			X*	X*		X*	X	X	X	X	X*	X	X
	≥3		X	X	X		X	X	X*	X*	X	X	X	X
	≥4		X	X	X		X	X	X	X	X	X	X	X
Daily max heat index (HI_max)	≥2			X*	X*		X*	X*			X*	X*	X*	X*
	≥3		X*	X	X		X*	X			X*	X*	X	X
	≥4		X*	X	X		X	X			X	X	X	X
Daily max and min temp (T_max and T_min.)	≥3	X*
Huth^a	≥3					X*

Per Huth's definition, a heat wave is defined as the longest period of consecutive days satisfying the following three conditions: 1) the daily maximum temperature is above Tl (97. 5th percentile) for at least three consecutive days; 2) the daily maximum temperature is above T2 (81 th percentile) during the entire period; and 3) the average of daily maximum temperature over the entire period is greater than Tl.