What causes a Heatwave?

What causes these fluctuations in summer weather from one week to the next?

by Jaime McLeod Updated: January 17, 2024

The Farmers’ Almanac is calling for steamy, stormy, and sultry weather for many regions of the U.S. and Canada this summer. Depending on how you feel about heat, that may or may not be welcome news.

But what causes a heatwave, anyway? Why can we have a wet, chilly summer one year and a sizzler the next? Or even between one week and the next?

Heat exhaustion and heatstroke - Fatigue

According to NOAA, a heatwave is defined as a period of unusually hot weather that typically lasts two or more days. To be considered a heatwave, the temperatures have to be outside the historical averages for a given area.

A heatwave occurs when there is a weather system in place that traps hot air in an area, preventing it from dissipating. This can happen due to a high-pressure system or stagnant air mass. Additionally, heatwaves can be exacerbated by factors such as urbanization, the heat island effect, and climate change.

During a heatwave, the temperature rises significantly, leading to heat-related illnesses and potential dangers, such as dehydration and heatstroke. It is important to take preventative measures, such as staying hydrated, seeking shade, and avoiding intense physical activity during peak temperatures.

Overall, understanding what causes a heatwave is crucial in order to better prepare for and mitigate the risks associated with extreme heat events.

How Heatwaves Can Be Deadly

Longterm droughts are an example of climate change.

While the phrase “dangerous weather” may conjure up images of blizzards, hurricanes, or tornadoes, it’s important to remember that heatwaves can be deadly. Everyday things like a seatbelt, door handle, or bicycle can become extremely hot. When and during a heatwave, it’s good to try and limit your outdoor activity to early in the morning, or late in the evening.

And when humidity and dew points are high along with the temperatures, things can get very uncomfortable!

Jaime McLeod

Jaime McLeod is a longtime journalist who has written for a wide variety of newspapers, magazines, and websites, including MTV.com. She enjoys the outdoors, growing and eating organic food, and is interested in all aspects of natural wellness.