The summer of 2024 was the hottest summer since weather records began on Earth

While Southern California suffers the worst heatwave of the year, International climate officials have confirmed that the summer of 2024 was the hottest summer on record.

The global average temperature in June, July and August – known in the Northern Hemisphere as boreal summer – was a record-breaking 62.24 degrees, according to the European Union's Copernicus Climate Change Service. The season was marked by explosive wildfires, scorching heat waves and heat-related deaths in California and many other parts of the world.

“In the last three months of 2024, the globe experienced the hottest June and August, the hottest day on record and the hottest boreal summer on record,” said a statement from Samantha Burgess, deputy director of Copernicus. “This summer's temperature-related extreme events will only intensify, with more devastating consequences for people and the planet, unless we take urgent action to reduce greenhouse gas emissions.”

Not only was it a hot summer, but August was virtually the hottest August since weather records began in 2023, with a global average temperature of about 62.28 degrees, the agency said.

In fact, the entire year so far has been so warm that just four months before the start of 2024, it will almost certainly be the hottest year on Earth's record, surpassing 2023.

This is because the global average temperature anomaly between January and August was the highest ever recorded for this period – and 0.41 degrees warmer than the same period last year.

The average anomaly would have to decrease by more than half a degree for 2024 not to be warmer than 2023, which has never happened in the entire Copernicus dataset, the agency said.

A woman sunbathes in a park in Milan, Italy, during a July heatwave.

(Luca Bruno/Associated Press)

The seemingly endless series of record-breaking hot months is causing great concern among climate scientists and politicians as the planet approaches a dangerous tipping point.

“We are playing Russian roulette with our planet and need an exit from the highway to climate hell,” said António Guterres, Secretary-General of the United Nations, during a speech at the start of the record-breaking summer in June.

While rising temperatures on Earth are somewhat consistent with the upper limits of climate model projections, the heat has also exceeded some expectations, says Zeke Hausfather, a climate scientist at Berkeley Earth.

“The heat in 2024 has lasted longer than many of us expected, with the last few months comparable to the extremes we experienced in the second half of 2023,” Hausfather said in an email.

This is particularly puzzling because El Niño – a climate phenomenon associated with higher global temperatures – disappeared around the end of May but did not lead to the expected drop in global temperatures. There is usually a three-month lag between El Niño peaks and the global surface temperature response, “but even then we would have already started to see a slight cooling,” Hausfather said.

That conditions have remained consistently warm without El Niño may indicate that additional factors are at work, he said. Some theories include a change in aerosol transport rules that allowed more sunlight to reach Earth; an increase in the 11-year solar cycle; and the 2022 eruption of the Hunga Tonga-Hunga Ha'apai volcano, which may have trapped some heat in the atmosphere.

But even those factors “don’t seem to quite fit with what we’re seeing,” Hausfather said.

Also worrying is the steady rise in temperatures above the international limit of 2.7 degrees or 1.5 degrees Celsius set by nearly 200 nations under the 2015 Paris Climate Agreement to prevent the worst effects of global warming.

The limit is measured relative to the pre-industrial era, the time before humans began to significantly alter the planet's climate through greenhouse gases and other fossil fuel emissions, and is generally based on temperature data from 1850 to 1900.

August 2024 was the 13th month in a 14-month period that exceeded that limit. According to Copernicus, the global average temperature was about 2.72 degrees – or 1.51 degrees Celsius – above pre-industrial levels. The record was only broken in July, which was just below the limit for the first time in a year.

Experts say that while warming above the limit in a single year does not mean that humanity has officially exceeded the limit, it is a worrying trend that is going in the wrong direction.

“It is certainly a worrying sign that global temperatures have been consistently above 1.5 degrees Celsius for so long,” Hausfather said. He estimated the probability that 2024 will be the hottest year on record, even more so than 2023, at over 95%, and said it was also very likely that it would be the first year with a temperature above 1.5 degrees Celsius in the Copernicus dataset, although other datasets may disagree due to minor measurement differences.

Tourists walk with an umbrella in front of the Parthenon on the ancient Acropolis in central Athens in June.

(Petros Giannakouris/Associated Press)

And while summer was sweltering on land, the planet's oceans were also simmering. Record-warm oceans contributed to a fierce start to the Atlantic hurricane season this year, with Hurricane Beryl becoming the basin's earliest Category 5 hurricane on record when it formed in late June.

In August, the extent of Arctic sea ice also fell 17 percent below average – the fourth lowest value for that month in the satellite record and “significantly further below average than in the same month of the previous three years,” Copernicus officials said.

Antarctic sea ice extent was 7 percent below average, the second lowest extent for August in the satellite record.

The report comes as Southern California experiences several days in a row of triple-digit temperatures, including highs of over 101 degrees in some parts of Los Angeles County.

In fact, the summer was remarkably warm throughout the Golden State, with July being California’s hottest month since weather records began.

Officials at Death Valley National Park – where two people died of heat-related illnesses – confirmed that the park experienced its hottest summer on record, with nine consecutive days of 125 degrees or more. The park's average 24-hour temperature in June, July and August was 104.5 degrees, beating the previous record of 104.2 degrees set in 2021 and 2018.

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Daniel Swain, a climate scientist at UCLA, said the current heat wave is likely to break some daily records in Southern California, which has largely weathered this year's hot summer better than the rest of the state.

“It will almost certainly [bring] the hottest day of the year in much of Southern California and perhaps even the hottest day in several years in some parts of Southern California,” Swain said during a Information event on Wednesday“This is a significant heat event.”

In much of the region, nights are also likely to be the warmest for this time of year on record, he said.

“It may not sound as dramatic as, say, the hottest days on record or the hottest afternoon peak temperatures, but these nighttime temperatures are quite consequential from the perspective of impacts on human health, ecosystem health and also in terms of wildfires,” he said.

In fact, heat is the deadliest of all climate hazards, and a recent study confirmed that heat-related deaths in the United States are increasing.

The latest seasonal forecasts from the National Oceanic and Atmospheric Administration indicate that almost the entire country could experience above-average temperatures at least through November.

According to the National Weather Service, residents of Phoenix, Arizona, have endured temperatures above 100 degrees Fahrenheit for more than 100 consecutive days, breaking the previous record of 76 days set in 1993.