Residents of Buenos Aires were wearing shorts and fanning themselves as they struggled to cope with unusual heat on Tuesday. By Thursday, they were back in the jackets and scarves that they would normally wear at this time of the year.
The sudden change in wardrobe was the result of a heat wave gripping portions of South America, including Argentina, Chile and Paraguay, that are supposed to be experiencing winter.
Argentina’s capital city broke an 81-year-old daily temperature record on Tuesday, when the high reached 86 degrees Fahrenheit (or 30 degrees Celsius), according to the national weather service. Normally, highs in Buenos Aires this time of year are in the 60s.
“Climate change is not a distant scenario,” the service said in a Facebook post on Tuesday. “It is here, and it is urgent to act.”
This week’s heat wave in South America is part of a recent trend of abnormally high temperatures in the middle of the continent’s winter and also comes as countries in the Northern Hemisphere have faced record heat this summer.
Cristóbal Torres, a meteorologist with the Chilean weather bureau, said in an interview on Thursday that some of the nation’s cities have recorded some of the highest temperatures for the month of August in the past 30 years.
“It’s rare,” Mr. Torres said.
The record heat was being driven in part because of climate change and also El Niño, the global weather pattern that is often tied to intense heat, Mr. Torres said.
“These temperatures are going to keep on rising,” Mr. Torres said, referring to the effects of climate change.
With the temperature around 53 degrees Fahrenheit (11.7 Celsius) Thursday afternoon, Maria de los Angeles Lastoria, a psychologist, bundled up in her bright green scarf on her way to meet a friend for lunch in the Buenos Aires neighborhood of Palermo.
Just two days before, Ms. Lastoria, 53, said she had donned a T-shirt for a midday walk in her neighborhood. Although she tends to prefer warmer temperatures, she said, the burst of heat midwinter was a cause for concern.
“I don’t live this with happiness,” she said. “Maybe it’s because I’m older, but I am aware of the fact that this isn’t right.”
Temperatures in Buenos Aires returned closer to normal on Thursday, with highs in the 50s and 60s. But cities in northern Argentina and in portions of Chile and Paraguay were still expected to face the heat through the weekend, forecasters said.
Temperatures in Las Lomitas in northern Argentina, about 50 miles from the border with Paraguay, reached 97 degrees Fahrenheit (36 degrees Celsius), about 16 degrees higher than the normal high, according to Argentina’s national weather service.
Some cities in northern Chile were under heat advisories, with temperatures reaching 86 degrees Fahrenheit (30 degrees Celsius) this week, according to the Chilean weather service. Temperatures were expected to remain above normal through Friday, Mr. Torres said.
In cities across Paraguay, temperatures climbed to the upper 80s and 90s this week, about 15 to 20 degrees above normal on the Fahrenheit scale, according to Paraguay’s weather service. Forecasts indicated that the hot weather would stick around through the weekend, according to the weather service.
While temperatures in Buenos Aires are forecast to be closer to normal for the rest of the week, Ms. Lastoria said that she was worried about next summer, especially after portions of Europe faced record heat this summer.
“I don’t think 40 and 50 degrees are good for your health,” Ms. Lastoria said, referring to temperatures in Celsius, which would be about 104 and 122 degrees Fahrenheit.
On her way to catch a train in Buenos Aires after work on Thursday, Azul Marichalar, 21, said she didn’t know what to make of the winter heat.
“It’s very strange, this kind of heat in August,” Ms. Marichalar said. “It’s clearly not good, but that’s also our fault, with global warming.”