Summer arrives and the reactions couldn’t be more different.
Some people eagerly pull out shorts and sandals at the first sign of warm weather. They spend entire afternoons outdoors, soak up sunshine, and seem perfectly comfortable even when temperatures climb into the 90s.
Others have a very different experience.
They search for shade, stay close to air conditioning, and start feeling uncomfortable long before the temperature reaches what many would consider “hot.”
It raises an interesting question: Why do people respond so differently to summer heat?
The answer turns out to be more complicated than simple preference. While personal tastes certainly play a role, researchers have found that heat tolerance is influenced by a combination of biology, health, age, fitness, and even where a person lives.
In other words, if summer heat feels overwhelming to you, it may not be all in your head.
How the Body Stays Cool
The human body works hard to maintain a relatively stable internal temperature.
When temperatures rise, the body activates several cooling mechanisms. Blood vessels near the skin surface widen, allowing heat to escape more easily. Sweat glands produce moisture that evaporates from the skin, carrying heat away with it.
These systems are remarkably effective, but they don’t work equally well for everyone.
Factors that affect circulation, sweating, hydration, and overall health can influence how comfortably a person handles hot weather.
That’s one reason two people standing side-by-side can have completely different reactions to the same summer afternoon.
Age Makes a Difference
One of the strongest influences on heat tolerance is age.
Older adults often have a harder time adapting to high temperatures. As people age, the body’s cooling systems may become less efficient. Sweating responses can change, circulation may be affected, and the sensation of thirst may become less noticeable.
Young children face challenges as well.
Children produce more body heat relative to their size and may not recognize early signs of overheating as quickly as adults. They can also become dehydrated faster during outdoor activities.
For many healthy adults, the body is generally at its peak ability to regulate temperature during middle adulthood, though individual differences still exist.
Fitness Levels Matter
People who exercise regularly often develop greater tolerance to heat.
This doesn’t mean athletes enjoy hot weather more than everyone else, but their bodies may adapt more efficiently.
Regular physical activity can improve circulation and help the body become better at cooling itself during exertion. People who spend time exercising outdoors may also become gradually acclimated to warmer conditions.
Researchers refer to this as heat adaptation or heat acclimatization.
The body essentially learns how to manage heat more effectively after repeated exposure.
That’s one reason the first hot days of summer often feel especially uncomfortable. Most people haven’t yet adapted to the seasonal change.
Body Size and Composition Play a Role
Heat tolerance can also be influenced by body composition.
Larger bodies generally generate more heat and may retain heat differently than smaller bodies. Excess body fat can act as insulation, making it more difficult for the body to release heat efficiently.
That doesn’t mean every larger person struggles in the heat or that every smaller person enjoys it. Human physiology is far too complex for simple rules.
However, body composition is one factor among many that can affect how a person experiences summer weather.
Some Medical Conditions Increase Heat Sensitivity
Certain health conditions can make hot weather more difficult.
Conditions that affect the heart, circulation, lungs, or metabolism may influence the body’s ability to regulate temperature.
People living with diabetes, for example, may sometimes experience changes in sweating, circulation, or hydration status that can affect comfort during hot weather.
Some neurological conditions can also interfere with the body’s cooling mechanisms.
Even temporary illnesses such as fever, infections, or stomach bugs can make heat feel more intense.
This is one reason health experts often encourage people with chronic medical conditions to pay extra attention during periods of extreme heat.
Medications Can Affect Heat Tolerance
Many people don’t realize that certain medications may influence how the body responds to heat.
Some medications can affect sweating, hydration, circulation, or electrolyte balance. Others may make people more sensitive to sunlight.
Common examples include some medications used for blood pressure, allergies, mental health conditions, and other chronic illnesses.
That doesn’t mean people should stop taking prescribed medications during summer. Instead, it’s simply helpful to recognize that medication effects can contribute to differences in heat tolerance.
Anyone with concerns should discuss them with their healthcare provider or pharmacist.
Geography Shapes Expectations
Someone who lives in Arizona may react very differently to an 85-degree day than someone who lives in Oregon, Minnesota, or Maine.
Climate matters.
People who regularly experience hot temperatures often become physically and psychologically adapted to them over time.
Likewise, individuals who spend much of the year in cooler climates may find sudden heat waves particularly uncomfortable.
This adaptation isn’t permanent. It can diminish after extended periods away from warm conditions, which is why even lifelong residents of hot regions may struggle after spending significant time in cooler environments.
Why Humidity Changes Everything
Temperature tells only part of the story.
Humidity can dramatically influence how hot weather feels.
Sweating cools the body through evaporation. When humidity is high, sweat evaporates more slowly. As a result, the body’s natural cooling system becomes less efficient.
That’s why an 85-degree day with high humidity can sometimes feel more uncomfortable than a much hotter day in a dry climate.
Weather reports often include a “heat index,” which combines temperature and humidity to estimate how hot conditions actually feel to the human body.
Is It Possible to Be Genetically Better at Handling Heat?
Scientists are still studying this question, but genetics likely plays some role.
Researchers have identified genetic differences that may influence sweating patterns, circulation, metabolism, and other physiological responses related to temperature regulation.
However, genetics is only one piece of the puzzle.
Lifestyle, environment, health status, and repeated exposure to heat appear to have a significant impact as well.
Sometimes It Really Is Personal Preference
Not every difference comes down to biology.
People develop emotional associations with weather throughout their lives.
Someone who loves beach vacations, outdoor barbecues, and long summer evenings may naturally view hot weather more positively. Someone who dislikes sweating, sunburns, insects, or crowded outdoor events may have a less favorable perspective.
Psychology influences comfort more than many people realize.
Two individuals experiencing the exact same temperature may describe it very differently simply because they enjoy—or dislike—the season itself.
The Bottom Line
If you’ve ever wondered why some people thrive in summer heat while others count down the days until autumn arrives, science offers several possible explanations.
Age, fitness, body composition, medical conditions, medications, humidity, geography, and even genetics can all affect how the body responds to warm weather.
Personal preference still matters. Some people genuinely enjoy hot temperatures more than others.
But the next time a friend seems perfectly comfortable during a scorching summer afternoon while you’re searching for the nearest air-conditioned building, remember: it may not be a matter of toughness at all.
Their body may simply be handling the heat differently than yours.
