Why Heat Feels Easier in a Dry Climate but More Exhausting in Humid Conditions

During summer, when air temperatures rise, it becomes clear that heat is felt very differently from one place to another. In some regions, high temperatures cause little discomfort, while in others the same level of heat feels almost unbearable. The main reason for this difference lies in air humidity. For the human body, what matters is not only the air temperature itself, but how that temperature affects the body.

Air humidity refers to the amount of water vapor present in the air. It is measured as a percentage and shows how much moisture the air contains compared to the maximum amount it can hold at a given temperature. For example, a relative humidity of fifty percent does not mean that the air is half water. It simply means that the air is holding half of the moisture it could possibly contain at that temperature.

To cool itself in hot conditions, the human body relies on sweating. When sweat appears on the skin and evaporates, it removes excess heat from the body. Thanks to this process, the body can avoid overheating and maintain a stable internal balance. In dry climates, where the air contains little moisture, sweat evaporates quickly, making the cooling process efficient.

In humid climates, this mechanism works much less effectively. Because the air is already saturated with water vapor, sweat evaporates slowly or may not evaporate at all. As a result, the body cannot cool itself properly, and internal temperature begins to rise. This is why even moderate temperatures can feel extremely oppressive in areas with high humidity.

To better explain this phenomenon, scientists introduced the concept of the wet bulb thermometer. This measurement reflects the effect of sweating skin and shows the actual heat experienced by the human body, taking humidity into account rather than measuring air temperature alone.

Research shows that the human body can tolerate wet bulb temperatures of up to about thirty five degrees Celsius. Beyond this threshold, the body loses its ability to cool itself, leading to dangerous overheating. In recent years, as global average temperatures continue to rise, such conditions have become more frequent, highlighting the growing impact of climate change on human health.