Sometime in late October, monarch butterflies that hatched in a field in Ontario or Michigan start flying south. It weighs about half a gram. It has never been more than a few kilometers from where it was born. Somewhere around the second week of November it lands in a fir forest on a mountainside in eastern Michoacán, in central Mexico, and it stops — along with several hundred million others, in a patch of trees you could walk across in twenty minutes.
Here’s the part that nobody has fully explained. That butterfly has never been to Michoacán. Its parents were never there either, or its grandparents. Four generations are born and die over the course of one annual cycle, and only the last one makes the long flight south — the great-great-grandchildren of the butterflies that left the same forest the previous spring. They arrive at the same mountains. Often the same stands of trees. Nobody showed them the way, because everybody who knew it died in Texas two generations ago.
A forest that turns orange and makes a sound becasue of Monarch butterflies
The Monarch Butterfly Biosphere Reserve covers 56,259 hectares straddling the border of Michoacán and the State of Mexico, about 100 kilometers northwest of Mexico City. UNESCO added it to the World Heritage List in 2008. The reason the butterflies choose this specific stretch of mountain and not somewhere else comes down to a tree: the oyamel fir, Abies religiosa, which grows in Mexico between roughly 2,400 and 3,600 meters above sea level and almost nowhere else in the quantity the monarchs need. The canopy holds a narrow band of temperature — cold enough that the butterflies burn barely any energy over the winter, not so cold that they freeze. It’s a five-month cold room with a roof, and there are only a handful of them on earth.
What you see when you get up there doesn’t photograph properly, and everyone who has been will tell you the same thing. From a distance the fir branches look dead — heavy, drooping, covered in something brown and shingled, like bark that’s come loose. Then the sun clears the ridge, the temperature rises a few degrees, and the trees come apart. Millions of butterflies open at once and go up into the air, and the brown becomes orange, and the whole slope moves. And there’s a sound. Monarch wings are silent one at a time. Half a million of them together make a dry rustle, somewhere between rain on a tent and paper being shuffled, and it’s the detail that ends up staying with people longer than the color does.
The number that matters is measured in hectares
Scientists gave up counting monarchs a long time ago. There’s no honest way to count several hundred million insects clustered in a canopy, so instead the annual census — run by Mexico’s national protected-areas commission with WWF — measures the area of forest the colonies physically occupy, and reports it in hectares. Roughly 20 to 30 million butterflies fit in one hectare, which tells you how tightly they pack.
For the 2025–2026 winter, nine colonies were recorded — three in Michoacán, six in the State of Mexico — occupying 2.93 hectares. That’s a 64 percent increase over the previous winter’s 1.79 hectares, and it was reported as good news, correctly. It’s also well under the roughly 6 hectares researchers say the eastern migratory population needs to be considered stable. Both things are true at once. The migration is one of the more spectacular events in the natural world and it’s running at about half the size it should be, mostly because of what happened to the milkweed along the route north of the border rather than anything happening in Michoacán. Worth knowing before you go, and worth knowing that the ticket you buy at the sanctuary gate pays the local ejido communities who guard that forest from logging for five months a year.
Getting up the mountain
Three sanctuaries on the Michoacán side open to visitors: El Rosario, which is the largest and the one most people mean; Sierra Chincua, near the old mining town of Angangueo, with a shorter and gentler trail; and Senguio, which is quieter and barely visited by comparison. The season runs from about November to March. January and February are the peak — the colonies are at their densest, and the daily warm-up flights are the most reliable.
It’s a proper mountain visit, not a viewing platform. The trail at El Rosario climbs for the better part of an hour at around 3,000 meters, which is high enough that people who’ve flown in the day before feel it in their legs and their lungs. Horses are available for most of the way up. Guides are required, walking is slow and quiet by rule, and you get a limited stretch of time at the colony itself before you turn around. Go in the late morning — before about 11 a.m. the butterflies are still cold and clustered and motionless, and the thing you came for is the flight.
A few practical things people wish they’d known. It’s cold up there in January — the whole point of the place is that it’s a cold room — so bring layers even if you’ve come from a beach two days earlier, and expect to shed them by midday. Wear boots with grip; the trail is dust in a dry week and slick clay after rain. No perfume, no bug spray, and don’t reach for a butterfly that lands on you, which they will, because on a warm morning they land on everything. And bring more water than feels necessary, because thin air at 3,000 meters does the thing thin air does.
Base towns are Angangueo, a former silver-mining town wedged into a ravine, or Zitácuaro, which is larger and better served. From Morelia, El Rosario is around three to three and a half hours by road. From Mexico City it’s a similar distance from the other direction. Both cities sell it as a day trip and both day trips are brutally long — you leave at five in the morning, you climb a mountain at altitude, and you’re back after dark. Sleeping one night near the reserve turns the whole thing from an endurance event into a morning.
The lake the Purépecha never left
The butterflies are the reason most people come, and then Michoacán quietly does something else to them. Two hours west of the reserve, at 2,140 meters, is Pátzcuaro — a lake town of white walls and red-tiled roofs, wooden balconies and two enormous plazas, which was the seat of the Purépecha world before the Spanish arrived and one of the very few places in Mexico where the pre-Hispanic culture was never really displaced.
The Purépecha are the empire that beat the Aztecs. That’s not a local exaggeration — Tenochtitlán sent armies west and they lost, and the Purépecha kept their independence right up until the Spanish came, which is more than most of Mesoamerica managed. Their capital was Tzintzuntzan, on the lake shore, and its ruins are unlike any other archaeological site in the country: five yácatas, rounded keyhole-shaped stone platforms rather than the square stepped pyramids of the Maya and the Aztecs. The name means place of the hummingbirds.
Then came Vasco de Quiroga, a Spanish bishop who arrived in the 1530s and who Michoacán still calls Tata Vasco — grandfather Vasco. His idea was that every village around the lake should specialize in one craft and trade with the others, and the strange thing is that five centuries later it’s still how the place works. Santa Clara del Cobre still hammers copper by hand and holds a national copper fair that draws around 300 artisans. Paracho still makes guitars, and makes enough of them well enough to be the guitar-making town of Mexico. Tzintzuntzan works clay. You can drive a loop around the lake in a day and watch a 500-year-old economic plan still running.
And then there’s the night of November 1st into the 2nd, when Pátzcuaro becomes one of the most visited places in Mexico for a few hours. Families take candles and marigolds out to the island cemeteries on the lake — Janitzio most famously, the island with the forty-meter statue of Morelos on top — and stay with their dead until sunrise, with rowed boats crossing the black water carrying candles. It’s genuinely beautiful and it is also, now, extremely crowded. If you’re building a trip around it, book roughly a year out and get advice on which village to actually be in, because the smaller lakeside cemeteries hold the atmosphere better than the famous one does.
Morelia, the pink city almost nobody schedules
The state capital gets skipped by a remarkable number of people who fly through it, which is their loss. Morelia was founded in 1541 as Valladolid and renamed in 1828, and its entire historic center — over 200 colonial buildings — is cut from the same pink cantera stone, which gives it a single unbroken color that no other Mexican city has. UNESCO listed it in 1991. The cathedral’s baroque towers are around 60 meters, the second tallest of their kind in Mexico. The aqueduct, finished in 1789, runs about 1,700 meters through the middle of town on 253 arches, floodlit at night, with people eating dinner under it.
Morelia aqueduct, Michoacán, UNESCO World Heritage
Practically, it’s also the sensible base for all of the above. Morelia has an international airport, it’s three to four hours by road from Mexico City, an hour from Pátzcuaro, and about three hours from the butterfly sanctuaries — which makes it the one place you can sleep for several nights while doing entirely different things each day.
How to actually plan it
Michoacán rewards planning more than almost anywhere else in Mexico, for one blunt reason: everything here runs on a calendar and none of it waits for you. The monarchs are on the mountain November to March and gone by April. The Day of the Dead vigil is two nights. The best hour at the sanctuary is a 90-minute window on a warm morning. Get the timing wrong and you’ve driven a long way to look at a fir forest.
Lake Pátzcuaro and Janitzio island, Michoacán
The other reason is that this is a state where a good local operator is worth more than a good guidebook. Which sanctuary is holding the biggest colony this particular week, which road up from Angangueo is passable, which villages around the lake are the right ones on November 1st, which routes are the ones people actually use — that’s current, on-the-ground knowledge, not something you’ll get right from a laptop three months out. Marysol Travel has spent 18 years putting Mexico trips together with people on the ground who know it.
For incentive groups and small private trips it’s an unusually strong week, and a different flavor from the beach-and-boat version of Mexico. A morning on the mountain in the middle of a hundred million butterflies, an afternoon in a copper workshop with a hammer in your hand, dinner under a floodlit 18th-century aqueduct. It’s quiet, it’s physical, it isn’t a ballroom, and — this matters for a reward trip — nobody has already been. Michoacán isn’t on the standard incentive rotation, which is precisely the argument for it.
The butterflies will arrive in November whether or not anyone is there to watch. They’ll have flown some four thousand kilometers to a forest none of them has ever seen, and in March the survivors will start north again and die somewhere in Texas, leaving it to their great-grandchildren to come back. If you’d like to be standing under a fir tree the morning it happens, or you’re looking for somewhere to take a team that they won’t have been before, tell us what you’re thinking at marysoltravel.com/contact/ and we’ll build it around the season.
References:
- UNESCO World Heritage Centre — Monarch Butterfly Biosphere Reserve: https://whc.unesco.org/en/list/1290/
- WWF — Area of forest occupied by monarch butterfly colonies in Mexico, 2025–2026: https://www.worldwildlife.org/publications/area-of-forest-occupied-by-the-colonies-of-monarch-butterflies-in-mexico-during-the-overwintering-period-2025-2026/