Heat Waves and Their Effect on the Economy and You

How Much Do Heat Waves Cost Us? How Much Worse Will It Get?

Heat exhaustion

 Photo by Al Bello/Getty Images

A heat wave is a period of unusually hot weather lasting two or more days. The temperature is hotter than average for the region. In an extreme heat wave, temperatures will break records. The frequency, severity, and length of heat waves are increasing.


Heat waves are caused by a high pressure system that hovers over an area. It traps heat beneath it like an oven. High-pressure systems force air downward. Hot air on the ground cannot escape into higher levels. Without rising air, there are no rain or clouds. The sun just bakes the area until a new pressure system is strong enough to push the high-pressure system away.

Climate change increases heat waves by increasing the Earth's average temperature. How much has it warmed? Since the 1880s, the earth’s average temperature has risen 2.1 degrees Fahrenheit or 1.2 degrees Celsius. Global warming is occurring at a faster rate than at any other time in the Earth's history.

In the northern hemisphere, climate change alters the jet stream. The jet stream is created when cold Arctic air meets warmer southern air. As the Arctic warms, it slows the jet stream. That allows heat waves to linger. A study by Pennsylvania State University predicted that extreme weather in North America will increase 50 percent by 2100.


Over the past 30 years, heat waves have killed more people than all other weather-related natural disasters combined. Heat waves kill in four ways:

  1. Heat stress causes dehydration and loss of body salt. That throws off the chemistry of the body.
  2. As the body tries to cool, it taxes the heart. That can lead to failure in people with heart conditions.
  3. When the core body temperature rises beyond 104 F, organs fail. The gut leaks toxins into the body, creating a deadly inflammatory response called heat stroke.
  4. People drown while trying to cool off in lakes and rivers.

Heat waves are most likely to affect people who work or live outdoors. The Bureau of Labor Statistics estimates that more than 15 million U.S. workers have jobs that require them to be outdoors. Of those, 7 million are in construction, 5 million are in logistics, and 1.3 million are farmers. In July 2018, a United States Postal Service worker died on the job when the temperature hit 117 F.

Also at risk are those without air conditioning. Worker productivity declines by 2 percent for every degree Celsius above normal room temperature. The Environmental Protection Agency estimates that heat waves will cost the U.S. workforce 1.8 billion labor hours in the year 2100. That's $170 billion in lost wages.

The elderly, injured, and children are most threatened. People on certain medications that curb their ability to sweat are also at risk. Alcoholic consumption worsens the effect of heat waves.

By 2030, heat waves will lead to a $2 trillion loss in labor productivity, according to the International Labor Organization.

Heat waves contributed to the record wildfire season in the American West. The heat dried out vegetation, creating tinder for fires. Scientists were surprised that the heat was enough to overcome soil that was still moist from a wetter than normal winter. Wildfires are driven more by the temperature and moisture content in the air than by the moisture content in the soil.

Heat waves could be the reason behind the 45 to 75 percent decline in worldwide insect populations. Warmer temperatures make males less fertile by reducing sperm count, according to research by the University of East Anglia. It only took a 9 to 12 degree F spike over a five-day period to cut sperm count in half. A second spike almost sterilized the insects.


The Universal Ecological Fund estimates that heat waves and other climate change effects will cost the United States $360 billion per year by 2028. Much of this is due to health costs.

In 2016, health care costs were $3.3 trillion. That's 18 percent of the U.S. economy. That's up substantially from 1960, when costs were only $27.2 billion, or just 5 percent of gross domestic product. From 2002 through 2009, the health-related costs of heat waves was $5.3 billion.

Heat waves also lower food production. Between 1964 and 2007, drought and heat waves destroyed one-tenth of the world's cereal production.

National Weather Service Warnings

The U.S. National Weather Service notifies residents of upcoming heat waves. It uses a Heat Index Value also called the apparent temperature. It factors in humidity with the air temperature in degrees Fahrenheit.

The NWS issues a Heat Advisory when the heat index reaches a certain level within the next 12 to 24 hours. The trigger point depends on average temperatures and is different for each locality. The advisory may be issued for lower temperatures if it is early in the season or during a multi-day heat wave. A heat advisory means that people could be affected by heat. It warns them to take precautions. It also triggers public safety regulations. These can include a ban on evictions and electricity shutoffs.

The NWS issues an Excessive Heat Warning when higher heat levels are expected within the next 12 to 24 hours. At those temperatures, some people can be seriously affected or die if they don't take precautions. The warning alerts hospitals to prepare for an increase in emergency calls. It activate programs that check on the home-bound. Some cities will open public air-conditioned centers. It also triggers the same public safety regulations as a heat advisory.

An Excessive Heat Watch is a warning issued one to two days in advance of the heat wave.

Heat Wave 2018

In July 2018, heat waves set new temperature records all over the world. Death Valley had the hottest month ever recorded on Earth. In China, new monthly temperatures were set in 22 counties and cities. On July 5, 2018, Ouargla, Algeria, reported 124.34 F, the highest temperature reliably recorded in Africa. Climate scientists were shocked by the sudden onset of these extreme events.


A 2018 study predicted that heat waves will raise U.S. death rates by 2100. Northern states, such as Montana, North Dakota, and Minnesota, will see summer temperatures 11 F hotter by then. Heavily populated states, like New York, Pennsylvania, and Illinois, will see 10 F increases. The climate impact map shows you how much hotter your county will be over the next 85 years.

By 2100, heat waves and the other effects of global warming will cost the U.S. government $112 billion per year.