Although the threshold criteria may vary depending on the location, two kinds of heat-related alerts may be issued.
Issued when the heat, or combination of heat and humidity, is expected to become an inconvenience for much of the population, and a problem for some.
Excessive Heat Warning
Issued when the heat, or combination of heat and humidity, is expected to be dangerous for a large portion of the population.
A function of temperature and relative humidity, the combination of which results in what the hot and humid air feels like to the average person.
This is not the actual air temperature.