Home Emergency Management News What is a Heat Dome?

What is a Heat Dome?


Dangers of excessive heat

The recently covered heat dome phenomenon was new to me, so I'd imagine that it's new to many. Let's take a look at what it is and the dangers that it represents.

The current heat dome began forming over the central U.S. about a week ago. Compared to a heat wave, which behaves as a wave and passes through, the heat dome is very reluctant to move. In my case here in Kansas, it brought four straight days of 104 degree temperatures. Other locations across the country had similar experiences. As of now, the dome has slowly moved out of my area, where it will next challenge the eastern section of the U.S. next.

Heat causes deaths. The average number of people killed in the U.S. by heat each year is 113. Cumulative statistics for the current year are hard to find, but we know so far that five died in Arizona, five died in Michigan, and there have been numerous scattered deaths throughout many other states.

Heat domes explained

Here are a couple of resources, from NBC and CNN.

To summarize, a heat dome is a pocket of hot air that is trapped in the upper atmosphere and refuses to move. While it stagnates there, it heats everything around it, forcing hot air down to the ground, where the air lingers. The combination of hot air and humidity will drive the heat index much higher, making the event doubly dangerous.

For example, a 100-degree day could feel like 115 degrees under the right conditions. Once the heat index reaches 120 degrees, the situation becomes very dangerous. This has happened recently: Last year, the heat index reached 165 degrees in areas of Iran.

Additionally, one of the most dangerous features is that the temperature may not reduce very much at night. This makes an endangered person more endangered, and results in even more deaths.

Who is at risk?

It's not surprising to learn that the most at-risk individuals are the elderly, the very young, people who have heart and respiratory diseases, live without air conditioning, and/or are socially isolated without anyone to support and check on them. Cognizance and caring for people you know that are in these circumstances will save lives. And since that's the point of our EDM profession, let's make sure we carry out our duties.


  • Don't be stupid! Cars are killers. If you leave a pet or a child in a hot car, then you may return to a situation you would never want to deal with in your lifetime.
  • Listen to public safety officials! If they tell you not go outside, then don't go outside. If they tell you to get to an air-conditioned space, then do that. If they tell you to drink water, then do that. If you find yourself in a potentially dangerous situation, ask for help.
  • Know your community! Know your neighbor! It's heartbreaking to me, and should be heartbreaking to all of us, to read the stories of someone who died alone because nobody knew anything about their distress. As long as we profess to be the Greatest Nation on Earth and the Shining City on the Hill, that's unacceptable. I think we all understand that.

We can all survive this if we work together and do the right things--and most importantly, if we go out there and care for each other. So let's do that. Safe journey.

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Randall Cuthbert Dr. Randall Cuthbert is a retired APUS Professor of Emergency & Disaster Management. He has also worked as a Red Cross Shelter Supervisor, and spent a 20-year career as a US Air Force Civil Engineer Officer. His blogging interests include: protecting & enhancing the EDM profession in the areas of integrity, honorable public service, and social justice; education regarding the 'big picture' role of EDM in our society; educating our professionals and neighbors with regard to the greatest threat to our civilization--climate change; and in general terms, creating a better world for our children and grandchildren.