I received this email from one of our viewers, Gene Smith:
“In our science classes, there has been real discussion about what the ‘feels like’ temperature really means. Some believe it’s the more accurate measure. We didn’t have this years ago, and I think it’s being used to promote the climate change narrative. Please try to educate us all about what the real temperature is and occasionally give a lesson on how they’re different.”
Thanks for writing in, Gene. You’re asking a question that comes up a lot: Is the heat index, or “feels like” temperature, just a new way to hype the heat and push a climate change agenda?
The short answer: Not at all.
The heat index has been around since the late 1970s, long before climate change became a major focus in the media. It was developed by a scientist named Robert G. Steadman, who published work in 1979 on how heat and humidity affect the human body. His research focused on how we actually experience heat, especially when you factor in things like clothing and activity levels.
Even before that, meteorologists used a simpler tool called the Temperature-Humidity Index (THI), which aimed to describe how hot it feels in humid conditions.
What Steadman did was provide a more accurate and scientifically grounded way to measure what’s called the apparent temperature, how hot it feels to your body when you factor in both temperature and humidity.
So why didn’t we hear about the heat index much in the past? If you think back to the 1980s or 90s, you probably don’t remember your local weather person talking about the “feels like” temperature. That’s mostly because the technology to easily calculate and display it on-air didn’t exist yet, not because the concept was new.
What IS the Heat Index?
The heat index combines air temperature and relative humidity to describe how hot it feels to the average person. It assumes you’re in the shade with light wind. It does not factor in sunshine! If we add direct sunlight, it can “feel” 10 to 15 degrees hotter!
Here’s why it matters: High humidity makes it harder for sweat to evaporate, which is the body’s natural way to cool down. That means your body heats up faster and has a harder time cooling itself, making hot, humid days more dangerous.
The National Weather Service adopted Steadman’s calculations to better communicate heat-related risks to the public. Today, the heat index helps meteorologists issue heat advisories and warn people, especially those working or exercising outdoors, when the risk of heat illness is higher.
So no, the “feels like” temperature isn’t hype, and it’s not new. It’s a valuable tool rooted in decades of science to help people stay safe in the heat.
This is what the heat index scale looks like today.
How Our Bodies Cool Down—and Why Humidity Makes It Harder:
When our bodies get too hot, we have a built-in cooling system: we sweat.
As that sweat evaporates off our skin, it cools us down because evaporation is a cooling process. But here’s the catch: evaporation only works well when the air isn’t already full of moisture.
On hot and humid days, the atmosphere is already loaded with water vapor. That’s what we call high relative humidity. And when humidity is high, sweat can’t evaporate as easily. That means our bodies don’t cool off as efficiently, and we feel hotter than the actual air temperature. It’s not just uncomfortable, it can be dangerous.
Our bodies like to stay at a core temperature of around 98.6°F. If that rises to 104°F or more, we’re in heat stroke territory, which is a life-threatening emergency. That’s why heat safety is so critical, especially during hot and humid weather.
Now, on the flip side, low humidity makes a big difference. I remember playing golf in Phoenix one summer when it was 105°. But because it was a dry heat, it actually felt manageable. My body was able to sweat and cool itself efficiently, something that’s much harder to do in the sticky humidity of a Houston summer.
So next time you hear the heat index, or “feels like” temperature, think of it as your body’s reality check. It’s not just about the number on the thermometer. It’s about how your body responds to the environment around you.
Heat: The Number One Weather-Related Killer:
Heat is often called a silent killer,: and for good reason. Unlike hurricanes, floods, or tornadoes, you can’t see heat coming. It doesn’t leave behind dramatic damage, but it claims more lives each year than any other weather event.
While deaths from heat stroke make headlines, the real danger often lies beneath the surface. Extreme heat can worsen existing health conditions, triggering heart attacks, respiratory problems, and other serious complications. And here’s something most people don’t realize: heat-related deaths are often undercounted. For example, if someone has a heart attack during a heat wave, the cause of death may be listed as cardiac-related, even though it was the heat that pushed their body past the limit.
According to a 30-year average from 1995 to 2024, the U.S. sees about 238 heat-related deaths each year. That’s more than double the number of flood deaths (113), and more than three times as many as tornado deaths (73).
To bring it closer to home: more people died from heat after Hurricane Beryl in Houston than from the storm itself. It’s a sobering reminder that the danger doesn’t end when the wind dies down; the heat that follows can be just as deadly.
What Triggers a Heat Advisory or an Excessive Heat Warning?
When you see a heat advisory or excessive heat warning pop up on TV or your KPRC 2 Weather App, those alerts are based on the heat index, what the temperature feels like when you combine heat and humidity.
As of today, Houston isn’t under any heat alerts, but areas to our north and east are under heat advisories.
Here’s how it works for Houston:
- A Heat Advisory is issued when the actual temperature hits 103° or the heat index reaches 108°.
- An Excessive Heat Warning is issued when the actual temperature hits 105° or the heat index climbs to 113°.
These thresholds vary by region, but in Southeast Texas, we’re used to the heat, so it takes quite a bit for an alert to be issued. That said, even without an official advisory, it’s still important to take precautions when temperatures and humidity levels climb.
