How heat index values above 100 degrees impact you

MADISON, Wis. - Temperatures in the middle 90s and heat index values well into the triple digits are expected across southern Wisconsin over the next few days. 

However, how exactly does the "heat index" impact you when you're outside?

The heat index (or apparent temperature) is the temperature your body feels when you combine thermometer readings with the humidity. The humidity outside impacts your comfort level because it impacts your ability to sweat. 

Your body temperature should normally be close to 98.6 degrees. When your body temperature increases, sweat is released from your skin. The moisture from the sweat evaporates, and draws heat out of your body through evaporative cooling. This is the same process that cools the air down after a thunderstorm rolls through. 

However, on really humid days, sweat has a hard time evaporating from your skin. So during humid weather, your body temperature stays warm, thus creating a new temperature that your body feels when you're outside: the heat index.

Heat-related illnesses are possible with heat index values of 90 to 105 degrees. Once values start getting above 105 degrees, heat exhaustion and heat cramps are more likely and heat stroke is possible with prolonged exposure to the elements.

The heat index is a measurement of how the air feels to your body in shaded areas. If you are exposed to direct sunlight, the heat index can increase by up to 15 degrees.

Make sure to stay hydrated and take breaks in the shade if you are planning on being outside Thursday and Friday. 


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