This past weekend may have officially marked the start of spring in the Southern Hemisphere. Still, it felt more like the peak of summer in several countries, as extreme heat scorches South America with temperatures soaring above 40 degrees Celsius (104 degrees Fahrenheit).

Countries including Peru, Bolivia, Paraguay, Argentina, and Brazil have all witnessed record-breaking September temperatures, with some all-time high-temperature records at risk of being shattered as the heat persists throughout the week.

The exceptionally high temperatures result from a heat dome. This weather phenomenon occurs when a ridge of high pressure builds up over an area, trapping hot air for days or weeks. This phenomenon, where extreme heat scorches South America, has been exacerbated by El Niño, a natural climate pattern originating in the tropical Pacific Ocean, further amplified the heat. Additionally, the ongoing trend of human-induced global warming has contributed to these scorching temperatures.

Peru, in particular, has experienced some of the most extreme temperatures in September, a typically temperate month. For instance, the town of Puerto Esperanza witnessed temperatures surpassing 40 degrees Celsius, an infrequent occurrence for the country and just 1 degree Celsius shy of its all-time highest temperature of 41.1 degrees Celsius (106 degrees Fahrenheit).

Several other South American towns and cities also saw September heat records fall on Sunday, including:

• Filadelfia, western Paraguay, at 44.4 degrees Celsius (112 degrees Fahrenheit).
• Trinidad in Bolivia recorded 39.5 degrees Celsius (103 degrees Fahrenheit).
• Las Lomitas, Argentina, is experiencing 43.6 degrees Celsius (110 degrees Fahrenheit).

The extreme heat resulting from the heatwave was particularly widespread in Brazil, with temperatures soaring to 40 degrees Celsius in 11 states on Sunday, according to the weather company MetSul Meteorologia.

São Paulo reached 36.5 degrees Celsius (98 degrees Fahrenheit), marking the city’s highest September temperature since 1943, as reported by INMET, the national meteorological service. These scorching temperatures capped off São Paulo’s warmest winter in over six decades.

Listen it from the experts

As part of the ongoing extreme heat, the abnormally high temperatures have also increased the risk of wildfires in Brazil, which broke out in Bahia state last week. The extreme heat is expected to persist across parts of South America well into the coming week, with the potential for more temperature records to be broken. Maximiliano Herrera, a climatologist and weather historian who tracks extreme temperatures, stated, “More of the same – or worse – is unavoidable.”

Other parts of the Southern Hemisphere are also experiencing a boiling spring, including Australia, where unusually high temperatures and numerous bushfires are challenging the norm. According to Herrera, the country is witnessing “a September like none before, after the warmest winter on record.”

According to a recent climate research group Climate Central analysis, 98% of the world’s population experienced temperatures influenced by climate change between June and August.

“In every country we could analyze, including the Southern Hemisphere where this is the coolest time of year, we saw temperatures that would be difficult – and in some cases nearly impossible – without human-caused climate change,” noted Andrew Pershing, vice president of science for Climate Central, in a statement earlier this month.

Extreme heat is one of the clearest indicators of climate change as humans continue to burn fossil fuels that contribute to planetary warming. The Northern Hemisphere experienced its hottest summer this year, with June, July, and August each breaking global monthly heat records. As the abnormal heat persists, signs point to September becoming the record’s hottest month. According to the United States National Oceanic and Atmospheric Administration, there is a more than 93% chance this year will be the warmest on record.

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