Despite being the middle of winter in South America, the region is experiencing an unusual and intense heatwave, with temperatures soaring to unprecedented levels in Chile, Argentina, and surrounding locations. The latest spell of extreme heat has broken records, with the mercury rising above 100 degrees Fahrenheit (38 Celsius), setting an August record for Chile.
In Buenos Aires, where the average high on August 1st is 58 degrees Fahrenheit (14 Celsius), temperatures surpassed 86 degrees Fahrenheit (30 Celsius) on Tuesday. Weather historian Maximiliano Herrera took to Twitter to describe the situation as "one of the extreme events the world has ever seen," highlighting that this heatwave is defying all climatic norms.
What’s going on?
The most severe conditions have been observed in the southern half of the continent, especially in the Andes Mountains region. On Tuesday, temperatures climbed above 95 degrees Fahrenheit (35 Celsius) in numerous locations, even at elevations of approximately 3,500 to 4,500 feet in the Andes foothills. In some cases, temperatures exceeded 100 degrees Fahrenheit (38 Celsius), jumping significantly from morning lows in the 30s and 40s Fahrenheit (single digits Celsius).
Remarkably, some locations have recorded all-time maximum temperatures, surpassing even typical summer temperatures, despite being in the winter season. Climate data spanning 20 to 30 years reflects the exceptional nature of this heat compared to recent decades.
Scientists attribute this phenomenon to a powerful zone of high pressure, or heat dome, centered over Paraguay that is dominating the weather in South America. This high-pressure system extends from east to west across the south-central part of the continent.
Exceptional ongoing heat
Experts believe that climate change contributes to the likelihood of hot and persistent high-pressure zones in Australia, Africa, and certain island regions, where unusually warm winter temperatures have been reported.
In the Southern Hemisphere, August is equivalent to February in the Northern Hemisphere, and such high temperatures during this period are atypical. Weather historian Thierry Goose tweeted that Chile is experiencing an "extraordinary winter heatwave" as temperatures soared to 101.7 degrees Fahrenheit (38.7 Celsius), setting a national record for August.
Cities like Vicuña and Chiguinto in the central part of Chile recorded similar extreme temperatures on Tuesday, with afternoon highs reaching 40 to 45 degrees above normal (22 to 25 Celsius) for the date. Even overnight lows have been exceptionally warm, ranging from above freezing in the mountains to as high as the 70s Fahrenheit (mid-20s Celsius) in lower elevations.
The next few days are expected to continue with this prolonged heat spell, which began in late July. Paraguay recently set records of up to 98.6 degrees Fahrenheit (37 Celsius).
What’s causing the extreme heat?
Weather forecasts indicate that large zones of similarly extreme temperatures will persist at least into the weekend, as high-pressure systems maintain their influence. It is likely that temperatures between 95 and 104 degrees Fahrenheit (35 and 40 Celsius) will persist in the hottest spots in the coming days.
Blocking anticyclones can drive heatwaves in three main ways: Firstly, they pull warmer air from closer to the equator towards them. Secondly, the system compresses and traps the air, heating it up, as it did in the case of the 2021 heatwave in the Pacific Northwest, which shattered the Canadian temperature record by nearly 5°C. Lastly, the high pressure results in minimal ascending air and consequently, minimal cloud cover. This continuous absence of clouds allows the sun to continuously heat the land during the day, ultimately building up heat.
Reliable forecasts indicate that temperatures in the Andes region will remain 18 to 36 degrees Fahrenheit (10 to 20 Celsius) above average for an extended period. Some regions in southeastern South America may experience cooler weather.
As the region grapples with this extraordinary heatwave, concerns are growing over the implications of shifting climate patterns and the need for continued vigilance and preparedness to mitigate its impact on communities and ecosystems.
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