heat index intended to compute values up to about 136 degrees beyond levels the heat index was designed to compute heat index heat index heat index well into triple digits beyond levels the heat index was designed to compute intended to compute values up to about 136 degrees designed to compute values up to about 136 degrees http://www.nws.noaa.gov/os/heat/heat_index.shtml www.nws.noaa.gov beyond levels the heat index was designed to compute heat index