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Some of the country’s biggest cities, like Chicago, New York City and Boston, are bracing for what could be the hottest stretch of weather in 30 years this week as a sweltering heat dome settles over much of the Northeast and Midwest.

Over the next six days, 265 million people, or about 82% of the U.S. population, are likely to experience temperatures topping 90 degrees.

The National Weather Services says this is a rare and long-duration heat with up to five straight days of 95-plus-degree weather with high humidity that will make it feel 100 to 105 degrees for many.

Out west, dangerous heat is also expected for Texas, Arizona, Nevada and New Mexico. An excessive heat warning was issued for Phoenix and Tucson, Arizona, where temperatures threatened to hit the 110-degree mark on Sunday.

A warming climate trend

The warmer weather is trend. 2023 was the warmest year since global records began in 1850 at 1.18°C (2.12°F) above the 20th-century average of 13.9°C (57.0°F). Remember, the world’s most important climate goal is limiting the Earth’s warming to 1.5 degrees Celsius (2.7º F).

The 10 warmest years in the 174-year record have all occurred during the last decade (2014–2023).

According to NCEI’s Global Annual Temperature Rankings Outlook, there is a 61% chance that 2024 will rank as the warmest year on record and a 100% chance that it will rank in the top five of warmest years recorded.

Climate and human health

So how are humans doing in this warming world? Not good. There has been a significant increase in heat related deaths.

In the U.S., there was approximately 1,602 heat related deaths occurred in 2021, 1,722 in 2022, and 2,302 in 2023.

That means that 2023 had a 34% increase from 2022 heat-related deaths across the country.

Human health concerns

Climate warming will continue to impact human health, particularly during periods of high temperatures. It can increase the risk of heat-related illnesses such as heat exhaustion and heat stroke. Prolonged exposure to high temperatures can also exacerbate chronic respiratory problems and cardiovascular disease.

You might be surprised to know that things don’t necessarily get safer at night.

In the past, people have found a brief respite from the heat when the sun went down. However, climate change is stoking higher temperatures deeper into the night, affecting people’s ability to sleep and recover.

The bigger impact of warming temperatures, especially during the summer months, is now at night.

In fact, there were 35 summer nights in Tampa in 2022 where the temperature did not drop below 80 degrees. These warmer temperatures at night make it more difficult for people and infrastructure to cool down and recover before more heat the following day.

Everyone is different

Another complicating element during a heat wave is that heat tolerance differs from person-to-person depending on a variety of factors, including age, gender and even where you are living. For example, a person from Miami who is used to the higher temperatures and humidity may face less risks than someone from a typically chilly city in Vermont during the same heat wave.

However, today, just days before summer begins, Burlington, Vermont, is expected to be about 10 degrees hotter than Miami.

While everyone is different, it is widely believed that a temperature of 95°F at 100% humidity or 115°F at 50% humidity is the maximum a human can endure before they can no longer adequately regulate their body temperature, which would potentially cause heat stroke or death over a prolonged exposure.

Last year, at least 645 people were killed by the heat in Maricopa County, Arizona, alone, according to the medical examiner’s office. People were dying in their cars and especially on the streets, where homelessness, drug abuse and mental illness made matters worse. Maricopa County will see temperatures as high as 114º this week.

Concerns this summer

Summer officially begins this Thursday, June 20, 2024. S​ummer 2024 is likely to be one of the hottest on record in the United States.

Last year, ambulances were dispatched tens of thousands of times after people dropped from the heat. It was relentless and didn’t give people a break, especially, as mentioned above, at night. The heat of 2023 kept coming, and people kept dying.

Overall, the most at-risk individuals will be seniors, children and individuals with chronic health conditions, but heat waves can be dangerous for any person.

Signs of heat stress to keep an eye out for include dizziness, fatigue, muscle cramps, clammy skin and nausea. In some cases, these symptoms can turn deadly.

Annual Florida Climate Conference

The theme of the 2024 CAC Florida Climate Conference will be Climate and Human Health. This year’s edition of this popular event will be held November 14-15, 2024, in the brand new conference facility at the University of South Florida, Sarasota-Manatee campus.

The conference will feature some of the top medical, healthcare and climate experts in the world.

Subscribe to our newsletter below to get details about upcoming event and ticket sales.


The CAC is committed to the climate conversation. We do this with events like the Climate Champions Awards Ceremony, Hurricane Season Forecast Day and the upcoming Annual Climate Conference in November, that will focus on human health. We also give climate presentations, focused on adaptation strategies, to thousands of people throughout the year.

You can support us in helping our conversation going by making a donation or becoming a member.


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