Based on 3,094 research-grade iNaturalist observations in Colorado, Monarch is most often recorded in September; in Colorado it behaves like a summer visitor / breeder. It ranks #2 among butterflies recorded in the state in our data.
Danaus plexippus
Monarch in Colorado by month
Bars show research-grade observations per month. They mix true seasonality with how often people are outdoors, so treat small numbers with caution.
Also seen in Colorado in September
Painted Lady
Common Checkered-Skipper
Small White
Dainty Sulphur
Gray Hairstreak
Variegated Fritillary
Common Buckeye
Orange Sulphur
Places to look in Colorado
National ForestWhite River National Forest
Botanical GardenDenver Botanic Gardens
National ForestRio Grande National Forest
National ForestSan Juan National Forest
State ParkRoxborough State Park
State ParkMancos State Park
FAQ
When does Monarch appear in Colorado?
Mainly July–October, with the most records in September.
How common is Monarch in Colorado?
It ranks #2 by number of iNaturalist observations among butterflies in Colorado (3,094 records in our sample).