I am in a dream that cannot last. Of this I am sure. The trees that line my nighttime avenues are rich with purple flowers. They are crowded with birds. “Jacaranda!” I think. And yet I know it is not spring.

This dream is full of people dressed in sandals and short sleeves. It sounds like sellers unpacking crate after crate of fresas — strawberries — sent to the city straight from fields. I reach to taste one, and when I bite, I realize all of this is real.

I have defeated my fear of the winter ahead, if only for about 10 days.

A long flight south was what it took for my wife, Kathy, and me to replace the dwindling December daylight that we dread every year with its Southern Hemisphere opposite: an Argentine and Uruguayan spring. Down here, jacaranda and fresh berries are the order of the day along the boulevards of Buenos Aires, instead of coatings of snow.

Among the magic tricks of travel is changing climates and cultures overnight. Flipping seasons is at least as dramatic. It will tilt your body off its axis for days or even weeks at a time.

Along with our friends Kevin and Martha, we begin sneezing during our first Buenos Aires afternoon. “Pollen,” says Kevin, while staring hard at a street tree, a linden, that is spilling yellow blossoms like rain. “Anyone pack something for allergies?” No one has.

[What road movies tell us about travel — and ourselves]

The four of us can spend days together in a city that’s known for particular touchstones and end up passing on these altogether. Poking around is our thing.

So although we appreciate tango and enjoy wood-grilled steak, we find ourselves absorbed — and very often lost — in Buenos Aires’s quilt of districts.

Palermo, Recoleta, Congreso, San Martin. Some of the tiled shops and sculpted buildings we pass seem Italian. Then we cross a side street that feels like France and enter a tiny territory of Spain. There’s even some hard-to-place quirkiness in persistently strange store signs. A tapas place is known as “Man Cheese”; a hotel as “The Guido Palace.”

Soon we are smiling but also squinting through a sun­-brightened Plaza Armenia in the neighborhood of Palermo Soho. Fleets of radio taxis careen around corners at top speed, so we try to be cautious crossers. At one point, Martha notices that the city’s walk lights show a stick figure of a man running for his life. We take this as our cue.

Despite all the traffic, moving around seems oddly uncomplicated. I feel almost weightless and realize that it’s the switch from the corduroys I’d been wearing at home to a new pair of khaki shorts.

The Jardin Botanico, at the corner of Santa Fe and Las Heras avenues, looks like a jungle with a fence. It is as green as Brazil. A mockingbird welcomes us with imitations of birdsongs that we do not recognize. Bees and an oversized hummingbird are drinking from a jasmine vine. Even the robins look different. Hopping along paths of chopped clay tile, they are stocky, with stubby tails.

“I wonder if they’ve just arrived,” says Kathy.

“An early sign of the season,” I say without thinking. But then I begin to wonder. Do songbirds down here migrate north when autumn edges in during May?

***

After the bustle of Buenos Aires, Kathy and I decide to spend a few days by ourselves in a quieter capital that is a ferry ride across the Rio de la Plata. The sea-edged city of Montevideo — and the nation of Uruguay, the second-smallest in South America — are thought of as the Southern Hemisphere’s havens of liberalism. Same-sex marriage became legal here in 2013, and the sale and use of cannabis has been decriminalized.

It is only seconds after flagging a taxi that we hear this: “You like Trump? Or you do not like Trump?” Before I can begin to reply, the driver sends back his thoughts on the matter, punctuating his personal blend of English and Spanish with an emphatic thumbs-down.

It is our second day in town, so we decide to stop by Montevideo’s best-known landmark. The Palacio Salvo at Plaza Independencia is one of South America’s tallest buildings, and a piece of design that defies description.

As far as I can tell, the Palacio could be the work of award-­winning architects from Mars. Yes, I understand: The guidebooks and the plaque here credit the architect Mario Palanti. But I refuse to believe.

“Like no skyscraper I’ve ever seen,” says a similarly skeptical man standing next to me with a Nikon and tripod. “It’s too full of domes and outcroppings to be real.”

[For a decidedly French experience, visit Buenos Aires, ‘the Paris of Latin America’]

We escape its shadow at Plaza de la Constitucion, where there’s a flea market spread out and an open-air concert of amplified Spanish guitar. This is perhaps the fifth such display we’ve seen in our short time here.

In a way, the whole city of Montevideo moonlights as a

secondhand market. A shop selling pastries may have an old radio for sale in the window; a cafe might offer a few chipped tea settings or a collection of antique tableware.

There’s a part of me that’s still expecting a wind from winter to attack the plaza, scatter the knickknacks and force the guitarist indoors. But the air holds only softness.

The grass in the plaza is a green that could confound colored pencils. It is a tint with the potential to perplex even paint. More delicate than pigment, it flashes when sunlight hits it and reflects the brightness back.

Here at the fountain in the center of the park, it isn’t easy to work out which of the birds are ornate carvings and which are real ones waiting their turn for a drink. “There’s another robin,” Kathy notices. “And this one looks a little more like ours.”

Just as we follow its flight, a much larger shape charges into view. It’s a dog — a golden Labrador retriever — that chases birds to branches and peers over the fountain rim. A chord chimes out from the guitar.

When we look up, we see a different display of blossoms than in the Buenos Aires garden. Somehow smaller. Not quite linden. Not exactly jasmine. Not Argentine at all.

“Where am I?” I say to no one in particular. Kathy doesn’t wait to reply. “You’re very far from home,” she says.

She flashes me a smile. We both know where we are.

It is spring.

Mandel is a writer based in Providence, R.I. His website is petermandel.net.

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