July Was the Hottest Month Ever Recorded in the U.S. — Could August Be Even Worse?

July 2024 was the hottest July ever recorded across the contiguous United States, according to the National Oceanic and Atmospheric Administration, known as NOAA. The average temperature for the month was 76.9 degrees Fahrenheit — the highest since weather records began in 1895. Scientists say that human-caused climate change is the main reason temperatures have climbed so high. Now, as August gets underway, experts are watching closely to see if the heat will keep breaking records.

While temperatures are expected to dip for some parts of the country this week, NOAA's National Weather Service issued a strong warning about the South. "Potentially record-breaking heat will grip the Southeast to south-central U.S. into next week, with heat indices reaching 105-115 degrees Fahrenheit and little nighttime relief," the agency said. Heat index is a measure of how hot it actually feels when you factor in humidity. When the air is very humid, the body has a harder time cooling down, making the heat feel even more dangerous.

August is usually a little cooler than July, but weather experts say July's record sets the stage for more extreme heat this month. Some local temperature records have already been broken. Meteorologist Chris Bianchi shared on social media that Pueblo, Colorado, hit 107 degrees Fahrenheit — the hottest August temperature ever recorded there. That was just two degrees below Pueblo's all-time heat record for any month.

One surprising detail in NOAA's report was about nighttime temperatures. Daytime highs in July ranked only sixth-warmest on record, but overnight low temperatures were the warmest ever recorded, averaging 64.2 degrees Fahrenheit. That is 3.7 degrees above normal and beat the previous record set in July 2022. When nights stay hot, people and animals cannot cool down and recover from the heat of the day, which makes heat waves much more dangerous.

Scientists say the record heat is being driven by two major forces. The first is human-caused climate change, which happens when burning fossil fuels like oil, gas, and coal releases greenhouse gases into the air. These gases trap heat in the atmosphere, causing temperatures to rise around the world. The second force is a natural weather pattern called El Niño, which typically brings warmer temperatures to many parts of the globe.

El Niño is the warm phase of a larger climate pattern called the El Niño Southern Oscillation. It helps control weather all over the world, and it is expected to grow stronger in the months ahead. Climate scientist Michael Mann of the University of Pennsylvania said, "We expect to set record global temperatures as long as carbon emissions continue to warm the planet, and typically these records are set during major El Niño events." The combination of El Niño and climate change helped create the dangerous heat domes that covered parts of the U.S. in July, leading to dozens of deaths.

Climate scientist Katharine Jacobs of the University of Arizona agreed that the summer's extreme heat fits with what scientists have long predicted. "Extremely high temperatures across the continental U.S. this summer, along with intense drought and fire conditions, are absolutely consistent with the climate change signal," she said. In other words, the record heat is exactly what experts warned would happen as the planet warms. The United States was not alone — Europe also experienced its hottest July ever, according to the European Union's Copernicus Climate Change Service.

The news about July's record heat comes alongside a major climate report from the American Meteorological Society. That report looked at last year's extreme weather and found that levels of greenhouse gases, ocean heat, and global sea levels all reached their highest points on record in 2023. Scientists say these findings show that climate change is not slowing down — it is speeding up. Understanding these changes is the first step toward finding ways to protect people, animals, and communities from the dangers of a warming world.