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Waiting for location
NORTH AMERICAN MONARCH INTELLIGENCE
MONARCHS IN
CHICAGO
See the migration as a moving system: recent observations, your local timing window, today’s flight conditions, historical context and what to plant next.
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National map first. Your location unlocks a local migration forecast.
LOCAL MIGRATION DECISION
Chicago, Illinois monarch migration
Chicago sits on Lake Michigan, where shoreline geography and passing weather can shape how southbound monarchs move and concentrate.
This page runs the live Monarch Migration engine for Chicago, combining recent licensed observations, local seasonal timing, NWS flight conditions and historical occurrence context.
Nearby migration pages: Peninsula Point · South Bass Island · Cape May · Austin · San Antonio · Pacific Grove
YOUR LOCAL READOUT
Choose a location
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Historical timing baseline
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Licensed iNaturalist records, not butterflies counted
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NWS forecast
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Source coverage + observation density
Choose a location to answer the useful question: are monarchs moving through here now, and when should I watch?
OBSERVED + MODELED
The migration map
Recent sightings are direct observations. The timing layer is modeled. Keep those two ideas separate.
Observed recent licensed sighting
Modeled seasonal timing band
Great Lakes concentration/crossing context
Loading recent monarch observations…
What should I plant — and when?
Choose your location and the tool will change the guidance with the migration season.
01Milkweed for breeding
Native milkweeds are larval host plants. Establish them for the breeding season, not as a last-minute fall migration fix.
02Nectar for the journey
Late-season native flowers matter when southbound monarchs are refueling.
03Match local frost timing
Use your local planting and frost windows rather than a national one-date-fits-all rule.
Why monarchs can “stack up” on the lakes
During fall migration, shorelines, peninsulas, islands, headwinds and passing fronts can concentrate monarchs. They may stream along shore, gather before a crossing, or form overnight roosts.
500+monarchs have been documented in individual Great Lakes roost observations.
The Great Lakes layer marks known context areas; it does not claim every point is an active roost today.
MIGRATION IN 60 SECONDS
The trip is stranger than it looks
The orange dots are only the visible surface of a remarkable annual cycle.
Northbound takes generations
Spring recolonization is a relay. The butterflies reaching the northern breeding range are descendants of the monarchs that left Mexico.
Southbound is the marathon
The fall migratory generation can live for many months and eastern monarchs may travel more than 2,000 miles to central Mexico.
The wave has a clock
Latitude and the seasonal sun create a repeatable timing pattern, while fronts, wind and temperature can speed up, stall or concentrate the flight.
There are two major migrations
Eastern monarchs generally winter in Mexico. Western monarchs primarily use coastal California and northern Baja, with some mixing between populations.
LONG VIEW
Population trend ≠ today’s migration
Annual overwintering surveys tell us how the populations are doing. They should not be confused with the live map.
2.93 ha
Winter 2025–26 in Mexico
Area occupied by clustered eastern monarchs. Up from 1.79 ha the prior winter.
12,260
2025 mid-season count
Monarchs counted across 249 western overwintering sites — still near historic lows.
2026 surveysEarly: Oct 17–Nov 1Mid: Nov 14–Dec 6Late: Dec 26–Jan 10
YOUR AREA OVER TIME
Historical observation footprint
This is an observation index, not abundance. More observers and better platforms can create more records.
Choose a location to load commercially reusable GBIF occurrence history.
HOW THE ENGINE THINKS
One score, four ingredients
The score is deterministic and inspectable. If a source fails, the confidence falls instead of inventing precision.
Recent observations
Licensed community-science records near the selected location and whether reporting is rising or falling.
Historical timing
Published latitude-based arrival and fall peak phenology. Western locations receive less timing weight.
Flight weather
Temperature, precipitation and fall southbound tailwind from the National Weather Service.
Freshness
Stale or failed sources reduce the model instead of being silently treated as current.
PROVENANCE FIRST
What is live, what is historical, what is linked
OBSERVEDiNaturalistRecent monarch occurrence recordsCC0 / CC BY records only
LIVENational Weather ServiceHourly temperature, wind and precipitationOpen U.S. government data
HISTORICALGBIFLocal occurrence historyCC0 / CC BY only
MODELEDMonarch Watch phenologyLatitude migration timing baselinePublished reference parameters
LINKEDJourney NorthExceptional first-sighting / roost community scienceLinked, not republished on this commercial site