Heat Waves Explained — What Causes Them and Why They Kill

What Is a Heat Wave?

There is no universal definition, but a heat wave is generally a prolonged period (two or more days) of abnormally high temperatures for a given region. What counts as a heat wave in Finland would be a normal summer day in Dubai.

What Causes Heat Waves?

Most heat waves are caused by high-pressure systems (heat domes) that park over a region. These systems:

Trap hot air underneath like a lid
Suppress cloud formation and rain
Push the jet stream northward, cutting off cooler air
Allow the ground to heat progressively each day without overnight cooling

Why Heat Waves Are Deadly

Heat kills more people than hurricanes, tornadoes, and floods combined in many countries. The danger is:

Cumulative: Each consecutive hot day adds stress; the body cannot recover overnight
Invisible: Unlike storms, heat offers no dramatic visual warning
Disproportionate: The elderly, children, outdoor workers, and those without AC are most vulnerable

Heat Wave Safety

Hydrate constantly — do not wait until you are thirsty
Stay indoors during peak heat (11am-4pm)
Never leave people or pets in parked cars
Check on vulnerable neighbours daily
Recognise heat stroke signs: confusion, hot dry skin, rapid pulse — this is a medical emergency

Heat Stroke vs Heat Exhaustion

	Heat Exhaustion	Heat Stroke
Skin	Cool, clammy	Hot, dry
Temperature	Below 40°C	Above 40°C
Mental state	Tired, nauseous	Confused, delirious
Action	Cool down, hydrate	Call emergency services