August tied the hottest month on record, according to new climate data that also confirmed an exceptionally hot summer across the United States.
The National Oceanic and Atmospheric Administration reported this week that meteorological summer in the Lower 48, from June through August, was the warmest in 132 years of records. At the global scale, August matched July 2023 as the hottest month on record, according to the Copernicus Climate Change Service.
Copernicus said global average temperatures in August were 1.5 degrees Celsius, 2.7 degrees Fahrenheit, above pre-industrial levels, a threshold countries highlighted in the 2015 Paris climate agreement. Sea surface temperatures also hit record highs across the Pacific as El Niño developed.
A senior scientist at Copernicus, Francesca Guglielmo, said the numbers, while alarming, align with a long-running trend that scientists have tracked. “Measures need to be undertaken to try to mitigate as much as possible,” she said.
Copernicus data shows the global average temperature in August reached 62.53 degrees Fahrenheit. “What we’re feeling is not some regional heat anomaly, but a hotter climate all over the globe,” said Alexander Gershunov, a research meteorologist at the Scripps Institution of Oceanography at UC San Diego.
In the United States, August averaged 75.6 degrees Fahrenheit across the Lower 48, the warmest August on record. Daytime highs averaged 88.6 degrees, also a record, according to NOAA. Drought affected nearly 60% of the country over the summer.
“We’re just going to continue to hear about record-breaking heat, record-shattering heat over and over and over again,” said Daniel Swain, a climate scientist with the University of California Agriculture and Natural Resources. Guglielmo noted the real-world effects include higher demand for cooling and electricity, more drought, hotter oceans and greater wildfire risk.
What is causing the heat?
Scientists attribute the record heat primarily to human-caused climate change. “The number one reason is climate change. Full stop,” Swain said. Researchers increasingly quantify the link between extreme heat and greenhouse gas emissions, finding a contribution from human-caused warming to any record heat wave. El Niño, a natural climate pattern marked by abnormal warming of equatorial Pacific waters, developed this summer on top of that long-term warming and influenced global temperatures and weather patterns. “[El Niño] is a natural pattern that’s occurring in an unnaturally warming world,” Gershunov said.
How does heat impact people?
The summer’s heat brought severe impacts in Europe, where French officials recorded thousands of deaths. Western Europe had its hottest summer on record, Copernicus reported. In the U.S., tens of millions were under excessive heat advisories or warnings from the National Weather Service.
It is not only daytime heat that poses risks. NOAA reported above-average nighttime temperatures across most of the contiguous U.S. this summer. A Climate Central analysis in July estimated people worldwide lose about 56 hours of sleep per year due to heat. “The overnight heat can actually be even more dangerous than daytime heat because you never get that reset cycle,” Swain said.
NOAA expects September temperatures to remain above average, with elevated wildfire potential across parts of the Northwest and the southern U.S. Swain and other researchers say record heat will persist without steep reductions in fossil fuel emissions, which are the main driver of climate change. “We have got to bend that carbon curve,” Swain said.
Hottest month on record and impacts for Hawaiʻi
While these findings reflect global and national trends, Hawaiʻi is also sensitive to marine heat and El Niño conditions that can warm our surrounding waters, stress coral reefs and raise humid heat on land. Local agencies urge residents to stay hydrated, check on kūpuna and keiki during hot spells, and follow wildfire safety guidance as vegetation dries.
The pattern of August tying the hottest month on record echoes broader findings in August hottest month on record ties mark amid global heat. State and county resources in Hawaiʻi, including guidance from the Hawaiʻi State Department of Health, provide tips for staying safe during periods of extreme heat and poor air quality.
