11 Facts About Heat Waves. https://www.dosomething.org/facts/11-facts-about-heat-waves

1. A heat wave is a prolonged period of excessive heat, often combined with excessive humidity.
2. Excessive heat is determined by Heat Index Values. The heat index, also known as the apparent temperature, is what the temperature feels like to the human body when relative humidity is combined with the air temperature.
3. Summers in North America are hot, meaning most parts of the US experience heat waves during the summer. The region east of the Rockies tend feel heat waves with high temperature and humidity.
4. If your pet stays outdoors during extreme heat, make sure they have cold water and an area out of the sun where they can cool off. For pets, spending time in a hot car can be super dangerous. 
5. Extreme heat can cause cramps, swelling, and fainting.
6. Heat waves kill more Americans than other natural disasters such as floods, lightning, tornadoes, and hurricanes.
7. Young children and adults over the age of 65 are most likely to experience heat exhaustion or other heat-related illness.
8. In July 1995, Chicago, Illinois experienced a heat wave that caused over 700 deaths. Scientists predict that the Midwest could endure similar heat waves up to 3 times a year by 2100 if greenhouse gas emissions continue to increase.
9. Urban areas often experience higher temperatures during the summer, referred to as “Urban Heat Island.” This is due to buildings, roads, and other infrastructures absorbing solar energy, resulting in higher temperatures.
10. Heat waves can cause blackouts and power outages, especially in areas that experience the urban heat island effect.
11. To stay hydrated during a heat wave, drink plenty of water and eat a salty snack to help replace the salt the body loses when it sweats.