Monarch Butterflies in California in September
Yes, September is a good month to see monarch butterflies in California. It is the 6th busiest month of the year, with 5,611 of the 61,044 sightings logged across the year (9.2%), based on verified iNaturalist records.
By Tim, founder of Easy Street Markets. I maintain the wildlife database and verify every animal and source myself. Updated June 28, 2026.
Good month for monarch butterflies in California
9.2%
of yearly sightings
5,611
records in September
#6
busiest month of 12
61,044
verified records a year
August 9.7%, September 9.2%, October 9.7%. Busiest month is July at 11.6%.
61,044 verified observations of monarch butterflies in California, recorded across 12 months of the year on iNaturalist.
When monarch butterflies are recorded in California
Peak month
July
7,074 records (11.6% of the year)
| Month | Observations | Share |
|---|---|---|
| January | 3,156 | 5.2% |
| February | 2,914 | 4.8% |
| March | 3,611 | 5.9% |
| April | 5,323 | 8.7% |
| Maypeak | 6,056 | 9.9% |
| Junepeak | 6,937 | 11.4% |
| Julypeak | 7,074 | 11.6% |
| August | 5,923 | 9.7% |
| September | 5,611 | 9.2% |
| October | 5,907 | 9.7% |
| November | 4,848 | 7.9% |
| December | 3,684 | 6% |
Monarch Butterflies you are most likely to see
| Species | Verified observations |
|---|---|
| Monarch | 61,044 |
In California, September carries 9.2% of the year's monarch butterflies sightings, about 0.9 points above an even month-to-month split. That makes it the 6th busiest of the twelve months, out of 12 months with recorded activity.
Activity holds steady between August and September, and it heads toward October (9.7%) after. The busiest month is July (11.6%), so if timing is flexible, that window is the safer bet.
The monarch butterflies most often recorded in California are Monarch. Those counts are annual totals rather than a September split, so treat them as which species you are likely to encounter, while the month figures above show how many sightings fall in September itself.
Which monarch butterflies you are most likely to see
- Monarch61,044 records
Plan your monarch butterfly trip in California
Start with live tours near Alcatraz Island, then compare a nearby stay and a broader wildlife backup before you lock in the trip.
GetYourGuide
Live tours nearbySee live tours near Alcatraz Island
Use the live GetYourGuide widget to compare local departures and activity styles close to the main monarch butterfly viewing area.
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Stay nearbyStay near Alcatraz Island
Compare hotels, cabins and lodges close to the best monarch butterfly viewing area in California.
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Broader backupBook a monarch butterfly tour in California
Compare guided wildlife tours, boat trips and nature experiences if you want a second travel network beyond the live widget.
Frequently asked questions
Can you see monarch butterflies in California in September?+
Yes. September accounts for 5,611 of the 61,044 verified monarch butterflies sightings logged in California across the year, which is 9.2% of the annual total.
Is September a good time to see monarch butterflies in California?+
September is the 6th busiest month. It is workable, though July and June is the stronger window for a reliable sighting.
What month is best for monarch butterflies in California?+
July is the single busiest month, with the broader peak running through July, June and May, based on 61,044 verified observations.
Which monarch butterflies are you most likely to see in California?+
The most-recorded species in California are Monarch, based on all-time iNaturalist counts.
See monarch butterflies in California in other months
More wildlife in California