We must educate ourselves about Wet Bulb Temperatures

Andrea T. Edwards, CSP
3 min readMay 3


A growing concern I have is the lack of awareness about what Wet Bulb Temperatures are and how close we are to hitting temperatures that can kill. To provide some context, my family lives in Phuket, Thailand, and on the 14th of April it recorded its hottest ever temperature at 45.4C. It was hot, but not Wet Bulb.

However, on the 25th of April, Thailand issued a ‘don’t go out’ warning for Bangkok, as the heat index hit a record of 54C. This is the moment where we must understand the difference between ‘the temperature’ and ‘the heat index’, because it’s the difference between life and death.

A temperature of 35C and a heat index of 54C is one degree under deadly Wet Bulb Temperatures — which is 55C — although it’s already deadly for many at 54C. Anything over 51C, the heat Index starts to get dangerous for the elderly, the pregnant and the sick.

If you’d like to learn more, especially those of us in the tropical region of the world, here is a scientific explanation of Wet Bulb Temperatures, a Guardian article, and Wikipedia’s version.

From the Guardian article: The “threshold” or “critical” Wet Bulb Temperature for humans, [is] the point at which a healthy person could survive for only six hours.

Not exactly as I said above, but there are a few contradictions in the information — aren’t there always? However, from all I’ve read, and Thailand’s response to a heat index of 54C, the average consensus seems to be a temperature of 35C and heat index of 55C is Wet Bulb.

How do you find it?

When you look at your weather app, if it says the temperature is 35C or higher, and the heat index (or feels like or real feel) temperature is 55C or higher, we are in Wet Bulb Temperature territory and that means even if you’re young and healthy, sitting in the shade with plenty of water, you can die.

Here’s my screen shot from the other day. It got hot!!

Wet Bulb Temperatures cook us from the inside out and if we have too much exposure to this heat, minutes matter in saving our lives. Here’s more information on the signs of heatstroke, by Business Insider.

The ‘feels like’ temperatures or ‘real feel’ or ‘heat index’ measures the amount of moisture in the air. As the world warms, for every .1 degree of warming, there is 7% more moisture in the air, and that is the deadly part, which is why we must start paying attention — especially if we live in humid countries.

In Asia, we are now in this territory, so I encourage everyone to understand Wet Bulb Temperatures, what it means, how to protect yourself, and if you’re in a place where these temperatures are already happening, please encourage your media, the government, and relevant businesses to start putting this information front and centre, because everyone needs to know.

We also need to protect the poor and the most vulnerable, who in the current situation, won’t stand a chance. We have to look at how they live and work, and we need to make sure that all of the risks are factored in. Please share this information with everyone you know in the Tropics. This is very important.



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Andrea T. Edwards, CSP

Inspiring leaders to own their voice with integrity & #UncommonCourage, a committed voice for a better future for all life on earth #SocialLeadership #Humanity