What is a Heat Wave

Heat Waves

Believe it or not, more deaths are attributed to heat waves in the United States than any other weather phenomenon.  They were determined to be about two and a half times more deadly than floods and more than ten times more deadly than hurricanes in 1992-2001 study.  In a single heat wave in 1995 in Chicago, over 700 deaths were reported in just five days as a result.  Perhaps it’s just that we’re doing a better job of recording the correct cause of death, but in recent decades, heat wave related deaths have increased. 

What is a Heat Wave

A heat wave is often defined by a prolonged period of abnormally high temperatures, and sometimes humidity.  They can last several days, and up to a few weeks long.  The fact is, experts can’t agree on single definition or set of thresholds for defining heat waves.  This is part of the reason reporting heat wave related deaths is so hard to do.

While heat waves are not in themselves preventable, protecting yourself from them often times is.  The best thing you can do during a heat wave is to stay out of the sun, particularly during the parts of the day that are the warmest.  This is especially true for young children and the elderly.  You should also drink copious amounts of water and avoid too much strenuous activity.

Another great way to protect yourself during a heat wave is to keep an eye on the heat index.   When paired with a heat index chart like the one below from the National Weather Service, it can provide valuable information regarding times of dangerous conditions that could lead to health issues or even a heat stroke.

Heat Index Chart


What Causes Heat Waves

We should talk about what causes heat waves.  A heat wave occurs when a high-pressure system gets trapped in an area for a period of time.  This happens when the air from above is sucked down towards the earth, compressing it and warming it up.  It really is an interesting phenomenon.   Because this warmed area is so pressurized, it pushes off new weather systems trying to come into the area.  This means it blocks winds from coming in and clouds from forming, thus no relief from the hot, stagnant air and a direct hit from the unrelenting sun.  In fact, the longer the heat wave lasts, the hotter it gets because of this.

Effects of Heat Waves on the Environment

In addition to heat strokes and the horrible loss of human life due to heat waves, there are also lots of effects of heat waves on the environment.  As mentioned above, heat waves or rarely accompanied by much rainfall.  It’s common, especially in certain parts of the country, that the combination of severe heat and lack of rain produces drought conditions and wildfires.  We all know how devastating wildfires can be as we see them in the news almost every year.  Statistics show that 4.5 million U.S. homes are at high or extremely high risk of wildfire.  Over 2 million of those are in California alone.

effects of heat waves on the environment

Moreover, crops fail or yield poor results during these drought conditions, which can lead to a lack of specific products in our food source.  Additionally, the increased use of air conditioning can lead to extensive power outages in the area.  Large transformers can sometimes explode under excessive temperatures and heavy humidity. 

Heat Wave Facts

  • Heat waves cause more deaths annually than any other natural disasters including floods, hurricanes, and tornadoes
  • The number of heat waves in the U.S. is increasing
  • The elderly, along with young children, are most susceptible to heat-related illness
  • Heat waves are often accompanied by drought conditions and can spur wildfires
  • Heat waves can be the cause of widespread blackouts
  • Heat waves are usually worse in large cities. They become urban heat islands
  • Overnight temperatures don’t drop like they normally would during heat waves

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