Heat Stress
Physical strain on the body when heat exposure exceeds its ability to cool itself, risking organ damage and collapse.
A condition in which the body's core temperature rises dangerously due to prolonged or intense heat exposure that overwhelms its cooling mechanisms. It occurs when environmental heat, physical exertion, or both exceed the body's capacity to dissipate warmth through sweating and blood flow. Symptoms range from heat exhaustion (fatigue, dizziness) to heat stroke (confusion, organ failure). It is a medical emergency requiring immediate cooling.
What this means in real life
A construction worker laboring in 95°F sun without shade or water breaks begins sweating heavily, feels dizzy, and can barely stand—classic signs the body is overwhelmed trying to shed excess heat.
What it isn’t
It is not simply feeling hot or uncomfortable. Heat stress is a measurable physiological emergency where core body temperature rises to unsafe levels; discomfort alone does not constitute heat stress.
Commonly misused online
Often conflated with 'heat wave' (an atmospheric event) or used casually to mean any hot day. Heat stress is specifically the body's dangerous response to thermal load, not the weather itself.