GENEVA — Earth has sweltered through its hottest Northern Hemisphere summer ever measured, with a record warm August capping a season of brutal and deadly temperatures, according to the World Meteorological Organization.
Last month was not only the hottest August scientists ever recorded by far with modern equipment, it was also the second hottest month measured, behind only July 2023, WMO and the European climate service Copernicus announced Wednesday.
August was about 1.5 degrees Celsius (2.7 degrees Fahrenheit) warmer than pre-industrial averages. That is the threshold that the world is trying not to pass, though scientists are more concerned about rises in temperatures over decades, not merely a blip over a month’s time.

Eric Gay
FILE - A cyclist tops a hill on a hot day at sunset, Aug. 20, 2023, in San Antonio. UN weather agency says Earth sweltered through the hottest summer ever as record heat in August capped a brutal, deadly three months in northern hemisphere. (AP Photo/Eric Gay, File)
The world’s oceans — more than 70% of the Earth’s surface — were the hottest ever recorded, nearly 21 C (69.8 F), and have set high temperature marks for three consecutive months, the WMO and Copernicus said.
“The dog days of summer are not just barking, they are biting,” United Nations Secretary-General Antonio Guterres said in a statement. “Climate breakdown has begun.”
So far, 2023 is the second hottest year on record, behind 2016, according to Copernicus.
Scientists blame ever warming human-caused climate change from the burning of coal, oil and natural gas with an extra push from a natural El Nino, which is a temporary warming of parts of the Pacific Ocean that changes weather worldwide. Usually an El Nino, which started earlier this year, adds extra heat to global temperatures but more so in its second year.
Climatologist Andrew Weaver said the numbers announced by WMO and Copernicus come as no surprise, bemoaning how governments have not appeared to take the issue of global warming seriously enough. He expressed concern that the public will just forget the issue when temperatures fall again.
“It’s time for global leaders to start telling the truth,” said Weaver, a professor at the School of Earth and Ocean Sciences at the University of Victoria in Canada. “We will not limit warming to 1.5 C; we will not limit warming to 2.0 C. It’s all hands on deck now to prevent 3.0 C global warming — a level of warming that will wreak havoc worldwide.”

Armando Franca
FILE - A World Youth Day volunteer uses a small fan to cool off from the intense heat, as he waits ahead of the Pope Francis arrival at Passeio MarÃtimo in Algés, just outside Lisbon, Aug. 6, 2023. UN weather agency says Earth sweltered through the hottest summer ever as record heat in August capped a brutal, deadly three months in northern hemisphere. (AP Photo/Armando Franca, File)
Copernicus, a division of the European Union’s space program, has records going back to 1940, but in the United Kingdom and the United States, global records go back to the mid 1800s and those weather and science agencies are expected to soon report that the summer was a record-breaker.
“What we are observing, not only new extremes but the persistence of these record-breaking conditions, and the impacts these have on both people and planet, are a clear consequence of the warming of the climate system,” Copernicus Climate Change Service Director Carlo Buontempo said.
Scientists have used tree rings, ice cores and other proxies to estimate that temperatures are now warmer than they have been in about 120,000 years. The world has been warmer before, but that was prior to human civilization, seas were much higher and the poles were not icy.

Ng Han Guan
FILE - Tourists eat popsicle and fan themselves to cool off from the humid weather in Beijing, Aug. 9, 2023. UN weather agency says Earth sweltered through the hottest summer ever as record heat in August capped a brutal, deadly three months in northern hemisphere.(AP Photo/Ng Han Guan, File)
So far, daily September temperatures are higher than what has been recorded before for this time of year, according to the University of Maine’s Climate Reanalyzer.
While the world’s air and oceans were setting records for heat, Antarctica continued to set records for low amounts of sea ice, the WMO said.
“Antarctic sea ice extent was literally off the charts, and the global sea surface temperature was once again at a new record,” WMO’s secretary-general, Petteri Taalas, said in a statement released to the media. “It is worth noting that this is happening BEFORE we see the full warming impact of the El Nino event, which typically plays out in the second year after it develops.”

Ohad Zwigenberg
FILE - Israelis and Palestinians bathe in a cool natural spring in the Judean Desert, West Bank, Aug 1, 2023. UN weather agency says Earth sweltered through the hottest summer ever as record heat in August capped a brutal, deadly three months in northern hemisphere.(AP Photo/Ohad Zwigenberg, File)
A strong El Nino coincided with the all-time high temperatures in 2016. The U.N. weather agency earlier this year rolled out predictions that suggest Earth would within the next five years have a year that averages 1.5 degrees Celsius warmer than in the mid 19th century. Each year at or near 1.5 matters.
It also predicted 98% chance of breaking the 2016 record between now and 2027.
The new readings on high global temperatures came as WMO released Wednesday its latest bulletin on air quality and climate, noting that extreme heat, compounded by wildfires and desert dust, has had a measurable impact on air quality, human health and the environment.

Daniel Cole
FILE - A man sunbathes in high temperatures in Marseille, southern France, Aug. 19, 2023. UN weather agency says Earth sweltered through the hottest summer ever as record heat in August capped a brutal, deadly three months in northern hemisphere. (AP Photo/Daniel Cole, File)
WMO scientific adviser Lorenzo Labrador lamented the deteriorating air quality around the globe and cited “record-breaking wildfire season” in many parts of the world, including western Canada and Europe.
“If heat waves increase as a result of El Nino, we may probably expect a further degradation in air quality as a whole,” he said.
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Borenstein reported from Washington.
Associated Press climate and environmental coverage receives support from several private foundations. See more about AP’s climate initiative here. The AP is solely responsible for all content.
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Michael Probst
A man rides a bike on a small road on the outskirts of Frankfurt, Germany, as the sun rises on Friday, July 7, 2023. (AP Photo/Michael Probst)
Michael Probst
A man rides a bike on a small road on the outskirts of Frankfurt, Germany, as the sun rises on Friday, July 7, 2023. (AP Photo/Michael Probst)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Kent Porter
The San Antonio Fire spreads uphill west of Petaluma, Ca., Friday, June 30, 2023. California is in the middle of a heat wave during the long Fourth of July weekend. (Kent Porter/The Press Democrat via AP)
Kent Porter
The San Antonio Fire spreads uphill west of Petaluma, Ca., Friday, June 30, 2023. California is in the middle of a heat wave during the long Fourth of July weekend. (Kent Porter/The Press Democrat via AP)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Jae C. Hong
A man does a flip while cooling off in the Dnieper River in Kyiv, Ukraine, Thursday, July 6, 2023. The planet's temperature spiked on Tuesday to its hottest day in decades and likely centuries. (AP Photo/Jae C. Hong)
Jae C. Hong
A man does a flip while cooling off in the Dnieper River in Kyiv, Ukraine, Thursday, July 6, 2023. The planet's temperature spiked on Tuesday to its hottest day in decades and likely centuries. (AP Photo/Jae C. Hong)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Charlie Riedel
Lucas Harrington, age 7, cools off in a mister at Kauffman Stadium as temperatures approach 100 degrees fahrenheit before a baseball game between the Kansas City Royals and the Cleveland Guardians, Wednesday, June 28, 2023, in Kansas City, Mo. (AP Photo/Charlie Riedel)
Charlie Riedel
Lucas Harrington, age 7, cools off in a mister at Kauffman Stadium as temperatures approach 100 degrees fahrenheit before a baseball game between the Kansas City Royals and the Cleveland Guardians, Wednesday, June 28, 2023, in Kansas City, Mo. (AP Photo/Charlie Riedel)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Kamran Jebreili
With the city skyline and Burj Khalifa, world's tallest building in background, people enjoy swimming in Dubai, United Arab Emirates, Wednesday, July 5, 2023. (AP Photo/Kamran Jebreili)
Kamran Jebreili
With the city skyline and Burj Khalifa, world's tallest building in background, people enjoy swimming in Dubai, United Arab Emirates, Wednesday, July 5, 2023. (AP Photo/Kamran Jebreili)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Alessandra Tarantino
Tourists take shelter with umbrellas as another one enjoys an ice cream during a hot summer day at the Rome's Spanish Steps Thursday, July 6, 2023. (AP Photo/Alessandra Tarantino)
Alessandra Tarantino
Tourists take shelter with umbrellas as another one enjoys an ice cream during a hot summer day at the Rome's Spanish Steps Thursday, July 6, 2023. (AP Photo/Alessandra Tarantino)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Andy Wong
A security guard wearing an electric fan on his neck wipes his sweat on a hot day in Beijing, Monday, July 3, 2023. (AP Photo/Andy Wong, File)
Andy Wong
A security guard wearing an electric fan on his neck wipes his sweat on a hot day in Beijing, Monday, July 3, 2023. (AP Photo/Andy Wong, File)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Andy Wong
A boy uses a national flag to shield from the sun as visitors line up to enter the Forbidden City on a sweltering day in Beijing, Friday, July 7, 2023. (AP Photo/Andy Wong)
Andy Wong
A boy uses a national flag to shield from the sun as visitors line up to enter the Forbidden City on a sweltering day in Beijing, Friday, July 7, 2023. (AP Photo/Andy Wong)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Gregorio Borgia
Tourists sips cold water as they shelter from a hot sunny afternoon near the Rome's Colosseum, Wednesday, July 5, 2023. (AP Photo/Gregorio Borgia)
Gregorio Borgia
Tourists sips cold water as they shelter from a hot sunny afternoon near the Rome's Colosseum, Wednesday, July 5, 2023. (AP Photo/Gregorio Borgia)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
LM Otero
Zoologist Kris Marshall uses a water canon to help an elephant keep cool from the heat at the Dallas Zoo in Dallas, Friday, June 30, 2023. (AP Photo/LM Otero)
LM Otero
Zoologist Kris Marshall uses a water canon to help an elephant keep cool from the heat at the Dallas Zoo in Dallas, Friday, June 30, 2023. (AP Photo/LM Otero)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Rafiq Maqbool
An Indian man stands at the door of his house as waves caused by high tide hits the huts on the shore of the Arabian Sea in Mumbai, India, Thursday, July 6, 2023. (AP Photo/Rafiq Maqbool)
Rafiq Maqbool
An Indian man stands at the door of his house as waves caused by high tide hits the huts on the shore of the Arabian Sea in Mumbai, India, Thursday, July 6, 2023. (AP Photo/Rafiq Maqbool)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Hadi Mizban
A woman sprays her children with a water hose during a heat wave outside his home in the al Fadhil neighborhood in Baghdad, Iraq, Thursday, July, 6, 2023. (AP Photo/Hadi Mizban)
Hadi Mizban
A woman sprays her children with a water hose during a heat wave outside his home in the al Fadhil neighborhood in Baghdad, Iraq, Thursday, July, 6, 2023. (AP Photo/Hadi Mizban)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Paul White
A man dives into the water from a platform at the Tranco reservoir near Beas de Segura, Jaen, in southern Spain, Thursday, July 6, 2023. (AP Photo/Paul White)
Paul White
A man dives into the water from a platform at the Tranco reservoir near Beas de Segura, Jaen, in southern Spain, Thursday, July 6, 2023. (AP Photo/Paul White)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Francisco Seco
Youngster dive into the Bosphorus next to Karakoy ferry terminal on a hot summer day in Istanbul, Turkey, Thursday, July 6, 2023. (AP Photo/Francisco Seco)
Francisco Seco
Youngster dive into the Bosphorus next to Karakoy ferry terminal on a hot summer day in Istanbul, Turkey, Thursday, July 6, 2023. (AP Photo/Francisco Seco)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Darren Calabrese
A woman carries her dog through a water fountain on the Halifax waterfront in Halifax, Nova Scotia, Thursday, July 6, 2023. (Darren Calabrese/The Canadian Press via AP)
Darren Calabrese
A woman carries her dog through a water fountain on the Halifax waterfront in Halifax, Nova Scotia, Thursday, July 6, 2023. (Darren Calabrese/The Canadian Press via AP)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Charlie Riedel
Los Angeles Dodgers third baseman Yonny Hernandez warms up before a baseball game against the Kansas City Royals Friday, June 30, 2023, in Kansas City, Mo. (AP Photo/Charlie Riedel)
Charlie Riedel
Los Angeles Dodgers third baseman Yonny Hernandez warms up before a baseball game against the Kansas City Royals Friday, June 30, 2023, in Kansas City, Mo. (AP Photo/Charlie Riedel)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Andy Wong
Visitors wear sun hats and carry umbrellas as they leave the Forbidden City on a hot day in Beijing, Thursday, June 29, 2023. (AP Photo/Andy Wong)
Andy Wong
Visitors wear sun hats and carry umbrellas as they leave the Forbidden City on a hot day in Beijing, Thursday, June 29, 2023. (AP Photo/Andy Wong)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
George Walker IV
Construction worker Fernando Padilla wipes his face as he works in the heat, Friday, June 30, 2023 in Nashville, Tenn. (AP Photo/George Walker IV)
George Walker IV
Construction worker Fernando Padilla wipes his face as he works in the heat, Friday, June 30, 2023 in Nashville, Tenn. (AP Photo/George Walker IV)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Aaron Favila
A man uses an umbrella to shield him from the afternoon sun in Manila, Philippines on Thursday, July 6, 2023. (AP Photo/Aaron Favila)
Aaron Favila
A man uses an umbrella to shield him from the afternoon sun in Manila, Philippines on Thursday, July 6, 2023. (AP Photo/Aaron Favila)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Rajanish Kakade
People enjoy high tide waves on the Arabian Sea coast in Mumbai, India, Thursday, July 6, 2023.(AP Photo/Rajanish Kakade)
Rajanish Kakade
People enjoy high tide waves on the Arabian Sea coast in Mumbai, India, Thursday, July 6, 2023.(AP Photo/Rajanish Kakade)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Mukhtar Khan
A Kashmiri man cools off at a stream on a hot summer day on the outskirts of Srinagar, Indian controlled Kashmir, Tuesday, July 4, 2023. (AP Photo/Mukhtar Khan)
Mukhtar Khan
A Kashmiri man cools off at a stream on a hot summer day on the outskirts of Srinagar, Indian controlled Kashmir, Tuesday, July 4, 2023. (AP Photo/Mukhtar Khan)
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Death Valley visitors drawn to the hottest spot on Earth during ongoing US heat wave
Andy Wong
A woman uses a fan to cool a child as they sit on a bench at Qianmen pedestrian shopping street on a hot day in Beijing, Thursday, June 29, 2023. (AP Photo/Andy Wong)
Andy Wong
A woman uses a fan to cool a child as they sit on a bench at Qianmen pedestrian shopping street on a hot day in Beijing, Thursday, June 29, 2023. (AP Photo/Andy Wong)