Jellyfishes in California in September
Yes, September is one of the best months to see jellyfishes in California. It is the 3rd busiest month of the year, with 1,194 of the 8,243 sightings logged across the year (14.5%), 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.
Peak month for jellyfishes in California
14.5%
of yearly sightings
1,194
records in September
#3
busiest month of 12
8,243
verified records a year
August 15.8%, September 14.5%, October 8.2%. Busiest month is August at 15.8%.
8,243 verified observations of jellyfishes in California, recorded across 12 months of the year on iNaturalist.
When jellyfishes are recorded in California
Peak month
August
1,300 records (15.8% of the year)
| Month | Observations | Share |
|---|---|---|
| January | 314 | 3.8% |
| February | 323 | 3.9% |
| March | 398 | 4.8% |
| April | 513 | 6.2% |
| May | 637 | 7.7% |
| June | 763 | 9.3% |
| Julypeak | 1,230 | 14.9% |
| Augustpeak | 1,300 | 15.8% |
| Septemberpeak | 1,194 | 14.5% |
| October | 678 | 8.2% |
| November | 480 | 5.8% |
| December | 413 | 5% |
Jellyfishes you are most likely to see
| Species | Verified observations |
|---|---|
| Greater Moon Jelly | 2,628 |
| Pacific Sea Nettle | 2,389 |
| Purple-striped Sea Nettle | 848 |
| Egg-yolk Jelly | 538 |
| Asian moon jellyfish | 175 |
| Australian Spotted Jelly | 26 |
| Black Jelly | 13 |
| Pacific Lion's Mane Jelly | 3 |
In California, September carries 14.5% of the year's jellyfishes sightings, about 6.2 points above an even month-to-month split. That makes it the 3rd busiest of the twelve months, out of 12 months with recorded activity.
Activity is easing off from August (15.8%) into September, and it heads toward October (8.2%) after. This is right inside the peak window, so September is one of the surest months to plan a trip around.
The jellyfishes most often recorded in California are Greater Moon Jelly, Pacific Sea Nettle and Purple-striped Sea Nettle. 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 jellyfishes you are most likely to see
- Greater Moon Jelly2,628 records
- Pacific Sea Nettle2,389 records
- Purple-striped Sea Nettle848 records
- Egg-yolk Jelly538 records
- Asian moon jellyfish175 records
- Australian Spotted Jelly26 records
Plan your jellyfish 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 jellyfish viewing area.
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Stay nearbyStay near Alcatraz Island
Compare hotels, cabins and lodges close to the best jellyfish viewing area in California.
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Broader backupBook a jellyfish 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 jellyfishes in California in September?+
Yes. September accounts for 1,194 of the 8,243 verified jellyfishes sightings logged in California across the year, which is 14.5% of the annual total.
Is September a good time to see jellyfishes in California?+
September is one of the best months. It ranks 3rd of the year and sits inside the peak window of August, July and September.
What month is best for jellyfishes in California?+
August is the single busiest month, with the broader peak running through August, July and September, based on 8,243 verified observations.
Which jellyfishes are you most likely to see in California?+
The most-recorded species in California are Greater Moon Jelly, Pacific Sea Nettle and Purple-striped Sea Nettle, based on all-time iNaturalist counts.
See jellyfishes in California in other months
More places to see jellyfishes
More wildlife in California