09/20/2026
A remarkable migration is passing over North America right now, often unnoticed above gardens, roadsides, parks, and backyards.
Every fall, millions of monarch butterflies travel south from the northern United States and southern Canada toward their wintering grounds. Some eastern monarchs may fly up to 3,000 miles to the mountain forests of central Mexico, even though the butterflies making the journey have never been there before.
West of the Rocky Mountains, monarchs follow a different route, moving toward the California coast and northern Baja California.
The timing depends on local conditions, especially temperature and day length. Migration can begin as early as August in southern Canada and the northern U.S., then move south through September and October. During the day, monarchs usually travel alone. At night, they may gather in trees, sometimes forming roosts with hundreds of butterflies.
This year’s migration comes after encouraging news from the eastern population. An annual World Wildlife Fund survey found monarchs overwintering in Mexico occupied 7.24 acres of forest during the 2025-2026 winter, up from 4.42 acres the year before, a 64% increase.
Scientists measure the forest area covered by colonies rather than counting individual butterflies, because it gives a more reliable picture of the population’s health.
Even with that increase, monarch numbers remain far below historic levels. In the late 1990s, colonies covered nearly 45 acres. Habitat loss, declining milkweed, pesticide exposure, and climate-related pressures continue to affect the species.
The migratory monarch was listed as endangered by the International Union for Conservation of Nature in 2022, and in 2024 the U.S. Fish and Wildlife Service proposed listing it as threatened under the Endangered Species Act.
For communities across Turtle Island, monarch migration is also a reminder of how connected landscapes are across borders. Native milkweed and nectar flowers can support monarchs along their route, especially when they bloom from spring through the first fall frost.
Have you seen monarchs moving through your area this season?