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3.2.8 Extreme Temperatures
Calculated Priority Risk Index
2.50 Moderate
Description
Planning Significance
Extreme temperature events, both hot and cold, can have severe impacts in Region L on human
health and mortality, natural ecosystems, agriculture, and other economic sectors.
Heat
According to the Centers for Disease Control and Prevention, 3,981 people died in the United
States from heat-related deaths during 1999 and 2005. Those at greatest risk for heat-related
illness include older adults and young children. However, even young and healthy individuals
are susceptible if they participate in strenuous physical activities during hot weather. Also,
during extreme heat events, infrastructure, energy sources in particular, can be stressed, and
long-term extreme heat can stress water sources, particularly if occurring during a period of
drought.
The contiguous United States now has the summer of 2012 as its third hottest summer on
record since recordkeeping began in 1895. According to NOAA’s National Climatic Data Center,
the average temperature for the contiguous United States between June and August was over
74 degrees F, which is more the 2 degrees above the twentieth-century average. Only the
summers of 2011 and 1936 have had higher summer temperatures.
According to information provided by FEMA, extreme heat is defined as temperatures that hover
10 degrees or more above the average high temperature for the region and last for several
weeks. Ambient air temperature is one component of heat conditions, with relative humidity
being the other. The relationship of these factors creates what is known as the apparent
temperature. The Heat Index chart shown in Figure 3.18 uses both of these factors to produce a
guide for the apparent temperature or relative intensity of heat conditions.
3.87