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:

1. Trap hot air underneath like a lid
2. Suppress cloud formation and rain
3. Push the jet stream northward, cutting off cooler air
4. 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

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