Buenos Aires is about to swing from a chilly 6°C morning to a 26°C afternoon in the span of four days, and for most of the country, the cold snap that gripped the nation this week is already old news. But in the far south, winter is refusing to leave quietly. Argentina is living through one of those September stretches when the calendar can't decide whether it's still winter or already spring — and Patagonia is the one region still voting for winter.
Buenos Aires Trades Its Chill for a Weekend Warm-Up
According to the National Meteorological Service's (SMN) extended forecast, Wednesday, September 16, will be the low point for the capital, with a morning reading of 6°C and a high that barely clears 15°C. From there, the recovery is steady and fast: 22°C on Thursday, 23°C on Friday, and a projected 26°C on Sunday — the warmest day forecasters currently have on the board, though cloud cover late in the day could bring a 10% chance of rain. That's a roughly 20-degree spread between the coldest morning and the mildest afternoon of the stretch, even though those extremes won't land on the same day.
The Cold Alert Has Already Expired
Here's where the story shifts from what was forecast to what's actually happening today. On Monday, the SMN's yellow alert for extreme cold reached eight provinces — Buenos Aires, Neuquén, Mendoza, San Luis, Córdoba, La Rioja, Catamarca, and Tucumán — a smaller footprint than Sunday's, when fifteen provinces were flagged in what forecasters called the coldest day of the month so far. By Tuesday, though, the SMN's own bulletin notes that no province remains under the sub-zero threshold that defines an extreme-cold alert. The only advisory still standing nationally is a wind warning for the southern tip of La Pampa, where gusts could hit 70 km/h. Buenos Aires City itself is forecast for a comfortable 18°C high today, ten degrees warmer than Monday's overnight low in parts of the interior.
Patagonia Still Isn't Ready to Let Go of Winter
The thaw hasn't reached the far south yet. Santa Cruz remains under a snow alert, and Monday brought the week's harshest reading anywhere in the country: Río Gallegos logged a wind chill of -10.3°C, edging out Malargüe and Chapelco for the coldest spot on the SMN's national ranking. The province's cordillera and plateau sectors are forecast to pick up between 10 and 20 centimeters of snow, with isolated spots potentially seeing more. Even so, there are early signs of relief: Río Gallegos' own Tuesday forecast calls for a far gentler -3°C low and 8°C high, suggesting the coldest city in the country is starting to turn the corner too. This week's chill followed an even sharper blast days earlier, when an orange alert warned of up to 40 centimeters of snow in northern Neuquén as a polar air mass swept across nearly the entire country.
The Countdown to Spring Is On
Timing helps explain why the seasons feel like they're arguing with each other. Argentina's astronomical spring doesn't officially start until the equinox, which the Naval Hydrography Service pins at 9:05 p.m. on September 22 — a day after the country's traditional Student's Day, when the equinox is popularly (if not astronomically) marked. A wobbly, back-and-forth handoff between the seasons is normal in this window, but this year's version is unusually dramatic: snow accumulating in the south while Buenos Aires flirts with nearly 30 degrees of temperature swing in the same week.
El Niño Is Quietly Setting the Table for Spring
Underneath this week's back-and-forth sits a bigger climate driver. The equatorial Pacific is running warm enough that the SMN's September bulletin puts the odds at 100% that the El Niño pattern holds through the September-to-November trimester, with an intensity it currently rates as strong to very strong. The World Meteorological Organization went further, warning that the episode "is clearly established" and is on track to intensify into a very strong event in the coming months. For Argentina's spring, forecasters see the best odds of above-average rainfall running from the northern Litoral through western Cuyo and into Patagonia's northeast, while central provinces are more likely to land near normal or slightly cooler than usual. Both the SMN and the WMO now put the odds near 100% that the warm phase persists all the way into February 2027, meaning this week's temperature whiplash is likely a preview, not an outlier, for the months ahead.
