Perceived Temperature

▣ What Is “Perceived Temperature”?

. 

Perceived temperature refers to the temperature that people actually feel, which takes into account not only the air temperature but also factors such as wind and humidity.

. 

In other words, even if the air temperature is the same, stronger winds or higher humidity can make it feel colder or hotter. Perceived temperature expresses this difference as a measurable value.

. 

In summer, it is typically determined by considering both air temperature and humidity. Humidity plays a key role because when it is high, sweat evaporates less efficiently, reducing the body’s ability to release heat—thereby increasing the risk of heat-related illnesses.

. 

. 

. 

▣ Concept of Perceived Temperature

Actual temperature	The air temperature measured with a thermometer.
Perceived temperature	The temperature felt by the human body, taking into account the effects of wind and humidity

. 

▣ Calculating Perceived Temperature

. 

1)  Summer perceived temperature – Calculated using air temperature and humidity (e.g., Heat Index)

2)  Winter perceived temperature – Calculated using wind speed and air temperature (e.g., formulas used by Environment Canada)

. 

▣ Perceived Temperature and Health

. 

• High perceived temperature – Increases the risk of heatstroke, dehydration, and cardiovascular problems.

• Low perceived temperature – Increases the risk of frostbite and hypothermia.. 

. 

▣ Heat Index

The heat index is a measurement used to estimate how hot it feels by combining air temperature and humidity.

. 

▣ Factors Affecting Perceived Temperature

. 

1) Summer: Humidity

• When humidity is high, sweat evaporates less efficiently, making it feel hotter and more uncomfortable.
• Example: At 33 °C with humidity above 80%, the perceived temperature can exceed 40 °C.

. 

2) Winter: Wind

• Wind increases heat loss from the skin, making it feel colder.
• Example: Even if the air temperature is 0 °C, strong winds can make it feel like –10 °C or colder.

.