Monarch butterflies follow a predictable annual calendar, so where they are right now depends on the time of year you’re reading this. In general, eastern monarchs spend November through February clustered in the oyamel fir forests of central Mexico, begin flying north into Texas in March, reach the central U.S. by late April and May, spread across the northern breeding range through summer, then funnel back south starting in August and September. Western monarchs overwinter along the California coast and head inland as early as February. Here’s how the full cycle breaks down so you can pinpoint where they are today.
November Through February: Overwintering
Eastern monarchs begin arriving at their mountain sanctuaries in central Mexico around the Day of the Dead celebration on November 2, with larger numbers settling in a week or so behind the leading edge. They cluster by the millions in a handful of high-altitude fir forests, spending the winter in a semi-dormant state. The most recent survey from the World Wildlife Fund found monarchs occupying four acres of forest during the 2024-2025 winter season, a 99% increase from the 2.2 acres measured the winter before. That’s encouraging, but total acreage remains a fraction of historical highs.
Western monarchs overwinter at coastal groves in California, mostly from November through February. The population is far smaller and in serious decline. The Xerces Society’s most recent Western Monarch Count found record-low numbers at many traditional sites. Natural Bridges State Beach in Santa Cruz recorded the highest count at 2,500 butterflies in early December. Other well-known sites like Pacific Grove Monarch Sanctuary in Monterey County held just 188 butterflies, and Pismo State Beach Monarch Grove tallied 471. Overall, western monarch numbers have declined roughly 10% per year since the 1980s. “The migration is collapsing,” said Emma Pelton, a senior conservation biologist with the Xerces Society.
March: The First Wave North
The overwintering generation breaks dormancy and begins moving north in March. Eastern monarchs push into Texas and the southern states, laying eggs on emerging milkweed and fueling up on nectar as they go. These are the same individuals that flew south months earlier, now completing their final act before dying. Their offspring will carry the migration forward.
Western monarchs leave the California coast in February and March, heading inland to find milkweed in valleys and foothills across the region west of the Rockies.
April Through May: The Next Generation Takes Over
By late April and into May, the first generation born in the southern U.S. picks up the northward push. These butterflies recolonize the central latitudes, moving through states like Oklahoma, Missouri, and Illinois. They live only a few weeks as adults, laying eggs and passing the baton to the next generation. This relay system means no single butterfly makes the entire round trip (except the overwintering “super generation,” which flew south the previous fall and started the spring return).
June Through August: Summer Breeding Range
Two to three summer generations spread across the northern breeding range, from the upper Midwest through the Great Lakes, southern Canada, and the northeastern U.S. Monarchs are scattered widely during these months, breeding wherever milkweed grows. Each summer generation lives about two to six weeks as an adult.
September Through October: The Super Generation Flies South
The final generation born in late summer is biologically different from every generation before it. Triggered by shortening days and cooling temperatures, these butterflies enter a state of reproductive pause, develop larger wings, and accumulate fat reserves for a flight that can cover 3,000 miles. Researchers have found that autumn-like conditions alone are enough to switch on these migratory traits, including a strong southwestern flight orientation.
This “super generation” can live eight to nine months, compared to the few weeks their parents and grandparents survived. They begin funneling south in late August and September, concentrating along flyways through the central U.S. and into Texas before crossing into Mexico by late October and early November.
How They Navigate Thousands of Miles
Monarchs use a time-compensated sun compass to stay on course. They track the sun’s position in the sky and adjust for its movement throughout the day using a biological clock. That clock doesn’t live in the brain. It resides in the antennae. Researchers discovered that antennal clocks operate independently, cycling in rhythm even when removed from the butterfly and studied in a dish. They’re directly set by light, functioning as the primary timing mechanism that keeps the compass calibrated. Monarchs also read polarized light patterns in the sky, processing visual information through both eyes and integrating it in a brain region that creates an internal map of the sun’s position.
When researchers removed or painted over monarchs’ antennae, the butterflies lost the ability to orient correctly, confirming the antennae aren’t just sensors for smell. They’re essential navigation hardware. Lab-raised monarchs that haven’t migrated for multiple generations show diminished wing size and weaker orientation ability, even when raised outdoors in fall conditions, suggesting migratory skill partly depends on being part of an active migrating population.
Track the Migration in Real Time
The best way to see exactly where monarchs are right now is through citizen science tracking projects. Journey North maintains an interactive map updated with sightings reported by volunteers across the U.S. and Canada. You can see first spring sightings, milkweed emergence, egg reports, and the fall migration wave as it moves south. The site lets you report your own sightings too.
For the western population, the Western Monarch Milkweed Mapper project compiles data on monarch locations and milkweed distribution across the western U.S. This collaborative effort helps identify important breeding areas and track how monarchs move through the landscape west of the Rockies. Both projects rely on everyday people reporting what they see in their yards, parks, and gardens.
Why the Migration Is Under Pressure
Habitat loss is the core threat on both sides of the Rockies. In California, over 60 documented overwintering sites have been destroyed since tracking began. In just the past year, at least three active sites suffered significant damage from tree removal. Development pressure continues at key groves: two overwintering sites at a Hayward golf course face threats from airport expansion plans, and eucalyptus trees at a Ventura site were slated for removal before community pushback paused the project.
Along the migration corridor, monarchs depend on milkweed for egg-laying and a wide variety of native wildflowers for nectar. Narrowleaf milkweed is a key host plant in the West. Planting native milkweed species appropriate to your region, along with nectar-rich wildflowers that bloom from spring through fall, directly supports whichever generation is passing through your area. Regional planting guides from the Xerces Society can help you match the right species to your location.