Summer is here, and it will start feeling like it. Temps will hit the 90s Thursday and will remain there through the weekend and into next week. Time to start thinking about heat and heat safety. Here’s how the National Weather Service decides when to issue Heat Watches and Warnings:
How Forecasters Decide Whether to Issue Excessive Heat Products
NOAA's heat alert procedures are based mainly on Heat Index Values. The Heat Index, sometimes referred to as the apparent temperature is given in degrees Fahrenheit. The Heat Index is a measure of how hot it really feels when relative humidity is factored with the actual air temperature.
To find the Heat Index temperature, look at the Heat Index chart below. As an example, if the air temperature is 96°F and the relative humidity is 65%, the heat index--how hot it feels--is 121°F.