Roaming South America

From the heat of the Amazon to the cold of the Andes

June 9, 2026

First, this blog is out of sequence. I wrote it and then forgot to add it to the schedule. So, here it is, a couple of months late.

Back on March 4, I arrived in Huancayo after spending about a month in Perú's Amazon region. It was warm, humid, and comfortable - T-shirt weather. Then I headed into the mountains. Since then, it’s been more than a month of higher elevations, colder air, and buildings with no heat. I don’t like the cold. Not just the outside cold, but the inside cold. The kind where you wake up and hesitate to leave the blankets because the room feels like a refrigerator.

The Andes have a particular kind of cold. The days can actually be pleasant. The sun comes out, and you might even think it’s warm. Then the sun drops, and the temperature falls quickly. With no insulation and no heating, the indoors simply follows the outdoors. Ten or twelve degrees Celsius might not sound terrible, but when it’s inside your room, inside the bathroom, and inside the bed sheets, it feels far colder than the number suggests.

Since leaving Oxapampa in the beautiful and warm Amazon, I’ve been moving steadily through this beautiful and very cold stretch of the Andes Mountains: Huancayo, Ayacucho, Cusco, Pisac, Sicuani, Ayaviri, Pucara, Juliaca, Puno, and more. Each one is high. Each one is cold. Each one with those cold nights. By the time I reach Bolivia, Cochabamba should be warmer during the day, but the nights still look rather cool. After more than a month in the mountains, I’ll probably arrive feeling like a big walking popsicle.

Looking Toward Warmer Regions

When I started looking at climate data, something interesting showed up. Once you drop off the Andes into southeastern Bolivia, northern Argentina, and Paraguay, the temperatures shift into a much more comfortable range. Warm days, mild nights, and far less of that dramatic swing between afternoon and midnight.

That nighttime temperature is the key. In the mountains, you might see a pleasant 22°C afternoon, followed by a 4°C night. In the lowlands, it’s more like 28°C during the day and 18°C at night. That 18°C night changes everything. The room stays comfortable. The bed isn’t cold. You wake up without bracing yourself for the floor.

Santa Cruz, Bolivia, sits right in that comfort zone. Southeastern Bolivia, in general, looks similar. Northern Argentina, places like Salta and Jujuy, also fall into that range. Paraguay, too, though Paraguay tends to push further into the hot side.

Encarnación: When Sand Becomes a Stove

I actually spent a couple of months in Encarnación, Paraguay, and that’s where I experienced the other extreme. One afternoon at the beach, a day when the temp was about 40°C (104° F), I took off my shoes and socks and headed toward the river. It was only a short run across the sand, maybe half a minute, and the bottoms of my feet were just about fried! I stayed in the water for a while, then ran back across the sand to my shoes.

In less than a minute total on that sand, my feet blistered.

It was that hot. The air temperature was already high, the sun was direct, and the sand had been baking all day. The surface temperature must have been extreme. By the time I reached my shoes, the damage was done. It was hotter than most days I remember in Tucson, Arizona.

That’s the difference between warm and hot. Encarnación in summer can push into the upper 30s Celsius, sometimes the low 40s, with warm nights that don’t cool down much. Santa Cruz and northern Argentina, on the other hand, usually sit in that more comfortable middle range. Warm days, but nights that are cool enough to make sleeping easy.

From Freezer to Comfortable

As of the day I'm writing this, I’m still in the freezer portion of the trip. High elevation. Cold nights. No heat in the hotel rooms. But the route ahead leads downhill, eventually, literally and figuratively. Cochabamba should be the transition. Santa Cruz should be comfortable. And beyond that, southeastern Bolivia, northern Argentina, and Paraguay all fall into that warmer belt. Right now, as I'm writing this, the phone shows a temperature of 8° C (46° F). Tonight it will drop to 5° C.

After more than a month in the Andes, that first warm evening where the air stays mild after sunset will probably feel like stepping back into summer, even though it's actually coming into winter in this hemisphere.