What Is Wet-Bulb Temperature? Why the Current June 2026 Day-Night Heatwave and Power Outages Are Exceptionally Dangerous

Wet-bulb temperature is becoming an increasing concern among scientists and researchers, as many regions are seeing a record number of extreme heat waves throughout June. The temperature that is recorded using a wet-bulb thermometer is thought by some to have a greater potential for causing negative health effects than an ambient temperature would individually.

What Is Wet-Bulb Temperature?

Wet-bulb temperatures measure the body’s ability to cool down through the evaporation of sweat from the skin. Wet-bulb temperatures are determined by taking into account both the air temperature and the relative humidity of the surrounding environment.

High humidity levels in the atmosphere slow down the rate at which sweat evaporates off of the body and thus prevents the body from successfully cooling down.

Why Is It So Dangerous?

When wet-bulb temperatures rise:

• Heat builds up inside the body
• Cooling becomes difficult
• Risk of heat exhaustion increases
• Heat stroke can develop more quickly

Why Night-Time Heat Makes Things Worse

The potential dangers of rising wet-bulb temperatures include:

• The accumulation of heat in the body
• The difficulty of cooling down and thus being at an increased risk for heat exhaustion
• The rapid onset of heat stroke (before the body is able to cool down) due to elevated wet-bulb temperatures

Traditionally, the temperature drops at night after the sun sets, which provides the body with time to cool down between the day and night.

The Added Risk of Power Outages

During heatwaves, if there are any power outages, then the following forms of protection from the heat will no longer be available to affected individuals:

• Cooling fans
• Air conditioning
• Refrigeration
• Cooling/evacuation centers

Final Words

Wet-bulb temperatures expose another danger created by heat waves, the interaction of heat and humidity. When excessive wet-bulb levels accompany hot nights and loss of power (especially air conditioning), then the ability of the body to cool itself is made extremely challenging. The risk is very important; therefore, precautions should be taken during prolonged extreme summer weather.

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