Here’s what the heat index is and why it matters

Heat-related illness often overlooked

File photo. (AP Photo/David Zalubowski) (David Zalubowski, Copyright 2021 The Associated Press. All rights reserved.)

Florida – The forecast in Florida summers is always hot, but when terms like “heat index” or “feels like” temperatures are brought into the mix, it’s not to hype up the heat forecast for entertainment. It’s mentioned because it can have extreme and even deadly impacts on the human body.

Heat index values aren’t some made up number. It’s the apparent temperature or what it feels like to our bodies when relative humidity is combined with the temperature.

Fun fact, these values are for the shade. When exposed to direct sunshine, the heat indices will be higher. These values are based off temperature and relative humidity like the chart below.

Chart provides heat index values based on relative humidity and temperature to account for the human body's comfort level. (NWS)

So, why does it matter?

The human body sweats in order to regulate body temperature when exposed to heat. Sweating is a good thing as it helps cool the skin to keep our bodies at a temperature that our organs can function normally under.

Think of it as natural air conditioner for the body. It’s what keeps us comfy. As the sweat evaporates off the skin, it causes the skin to cool down.

Shows the ranges of heat and the impacts it can have to the human body. (NWS)

When humidity is added to the equation, this is where our bodies run into problems. When there’s more moisture in the air, the rate at which the sweat evaporates off the skin decreases. If the air mass around us is drier, the body will feel cooler even in high heat. That’s why desert heat, although very hot, doesn’t feel as uncomfortable as tropical heat. When sweat doesn’t evaporate from the skin to cool it down, the body thinks it’s still hot and produces more sweat, forcing your body to work harder and making it difficult to regulate its temperature. This can lead to heat-related illnesses like heat stroke.

The CDC conducted a study from 2004-2018 showing that over 10,000 deaths in the United States were attributed to heat from May to September.

Here are some tips to stay safe when heat indices soar.

Summer safety tips: Signs of dehydration in kids, finding the right sunscreen

1. Stay hydrated. Drinking a good amount of water will help keep body temperature regulated and prevent dehydration.

2. Take breaks. This means giving your body some time to relax when outside working or when kids are playing.

3. Take a break in the shade to cool down. Whether participating in activities in the backyard or lounging at the beach, your body needs needs some time out of the direct sunshine. This can be done under a tree, umbrella, porch or, better yet, inside with air conditioning. It will also help prevent sunburns.

4. Wear appropriate clothing. Think light. Lightweight, light colors and loose-fitting clothing is best. Not only will this type of clothing allow your body to breathe, but the light colors reflect the sun unlike dark colors that absorb the heat.

5. Avoid hot and heavy meals. This type of food can actually add heat to the body, which results in the body working harder to stay cool.

6. Timing is everything. Try to plan outdoor activities earlier or later in the day. Peak heating happens around 3-4 p.m. Consider the time after noon as time the heat is building to reach the high temperature and then it slowly goes down as the sun reaches a lower point in the sky.

7. Don’t forget about pets. They need proper shelter from the direct sunshine and water to beat the heat, too.

About the Author:

Emmy Award Winning Meteorologist Samara Cokinos joined the News 6 team in September 2017. In her free time, she loves running and being outside.