Explaining the metric that tracks climate heat for health

• CNN explains that, as an index of heat, the wet bulb globe temperature uses a term to measure how heat stress affects people.
• For CNN, the index shows that heat stress can be determined by the level of humidity and, for people, by physical factors.
• Vox notes that, without the specific index, it is hard to understand the full picture, because the index is created to predict the health consequences of heat.

In a CNN article, it is stated that in the U.S., the average number of people who die from heat stress is 4 million. The author explains that the phrase “neck-deep in heat” is not a term for a specific index that can be used to predict the impact of heat.

CNN says that heat stress can be caused by high temperatures and humidity, and that in some cases it can lead to severe health effects. The article also notes that the risk is higher in certain regions.

CNN points out that the index can be used to understand how heat affects the human body. One of them — the heat index — describes how hot it feels when relative humidity is taken into account.

CNN also warns that the index can be misleading, because it does not fully reflect the real danger of heat. The article says that the wet bulb globe temperature takes into account multiple factors, including humidity, temperature, wind, and sunlight.

According to CNN, the wet bulb globe temperature can indicate when heat becomes dangerous for people. The article also notes that this index can show how heat affects the body even when temperatures are not extremely high.

Vox, in turn, argues that heat indices are not the same as real heat risk. In its material, Vox explains that heat stress can be influenced by many factors, including the ability of people to cool down and the availability of hydration.

Vox also says that the index is not a perfect measure, because it cannot account for all individual differences. Vox notes that heat risk depends on a person’s health, age, and other factors.

Vox provides a practical example: “Update, July 28, 2025, 11:45 am ET.” It states that, since 2023, the number of deaths related to extreme heat has increased, and it cites the specific index used in 2025.

Tags: Weather/Well-being/Research