The "unbelievable" mid-winter heat is "rewriting all climatic books," according to one expert, as the highest ever temperatures for this time of year have been recorded for many locations, with readings topping 100 F.

By Sophie Tanno, CNN

Published Aug 4, 2023 8:51 AM EST | Updated Aug 4, 2023 8:51 AM EST

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Smog caused by high temperatures in the city of Santiago on August 2. (Martin Bernetti/AFP/Getty Images)

(CNN) — Parts of South America are sweltering under abnormally hot temperatures – despite being in the depths of winter – as the combination of human-caused climate change and the arrival of El Niño feed into extreme winter heat.

Southern Cone countries including Chile and Argentina have experienced summer-like conditions as a heat wave, beginning in July, pushed temperatures higher than 38 degrees Celsius (100 Fahrenheit) in some places – dramatically above average for this time of year.

Maximiliano Herrera, a climatologist who tracks extreme temperatures across the globe, told CNN that South America is experiencing a “fierce winter heat wave.”

While such heat waves are not unheard of for the continent, this one has “exceptional characteristics for its area, duration, intensity and being early August,” Herrara said, adding “dozens of stations are recording their highest ever temperatures in the first half of August.”

August in the Southern Hemisphere is equivalent to February in the Northern Hemisphere.

Chile’s environment minister, Maisa Rojas, said that the world has been experiencing extreme events for weeks. “Yesterday it was the turn of South America and Chile,” she said in a Twitter post Wednesday.

In the mountainous Chilean Andes region, temperatures climbed to 38.9 degrees Celsius (102 Fahrenheit) on Tuesday, according to Herrara, who described the event as “unbelievable” for mid-winter and “rewriting all climatic books.”

In the Coquimbo region in northern Chile temperatures average around 22 degrees Celsius (72 Fahrenheit) in February, at the height of its summer. But this year, in mid-winter, they have soared far higher.

The commune of Vicuña reached 37.1 degrees Celsius (98.8 Fahrenheit) on August 2. “This temperature is the highest recorded in this period in all of Chile,” a spokesperson for the Meteorological Directorate of Chile told CNN.

It also marks the second-highest temperature on record for the country’s winter – which runs from June until August. Only in August 1951 was a higher temperature of 37.3 degrees Celsius (99.1 Fahrenheit) recorded in Copiapó.

“Tuesday was likely the warmest winter day in northern Chile in 72 years,” Raul Cordero, a climatologist at University of Groningen in the Netherlands, told CNN.

A woman uses an umbrella during an unusual winter period heatwave in Santiago, Chile, August 3. (Ivan Alvarado/Reuters)

In Argentina, some places reached highs of 38 degrees Celsius (100.4), according to the country’s national meteorological service.

The capital Buenos Aires – where August temperatures usually average 18 degrees Celsius (64.4 Fahrenheit) – experienced its hottest start to August in 117 years of data, with temperatures of just over 30 degrees Celsius (86 Fahrenheit) on August 1. This smashed the previous record for that day of 24.6 degrees Celsius (76.3 Fahrenheit) set in 1942.

For comparison, New Orleans’ average high the first week of February is also 18 degrees Celsius, and the city has never been above 28.3 degrees Celsius in the first week of February.

The high temperatures are expected to continue for the next five to six days, concentrated in Northern Argentina, Paraguay, Bolivia and southwest Brazil, where they could reach up to 40 degrees Celsius (104 Fahrenheit), Herrara told CNN on Wednesday.

Pushing temperatures ‘into the unknown’

“What we are experiencing is the combination of two phenomena: a global warming trend due to climate change plus the El Niño phenomenon,” Rojas said on Twitter.

El Niño, a natural climate pattern that originates in the tropical Pacific Ocean, brings warmer-than-average sea-surface temperatures and has a major influence on weather across the globe. Layered on top of global warming, caused by humans burning planet-warming fossil fuels, temperatures can reach record-breaking levels.

This extreme heat in parts of South America fits into a broader global pattern. July was the planet’s hottest month on record by a significant margin, and scientists found the heat waves that seared parts of the US, southern Europe and China in the Northern Hemisphere summer were made significantly more likely by the human-caused climate crisis.

“What to do? We know the solution: stop burning fossil fuels urgently!” Rojas said.

For Cordero, this winter’s unusual heat is alarming. “Just like the rest of the world, the combination of climate change and El Niño is pushing temperatures into the unknown,” he said.