Jellyfishes in Massachusetts in September
Yes, September is a good month to see jellyfishes in Massachusetts. It is the 6th busiest month of the year, with 178 of the 1,950 sightings logged across the year (9.1%), 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 jellyfishes in Massachusetts
9.1%
of yearly sightings
178
records in September
#6
busiest month of 12
1,950
verified records a year
August 15.1%, September 9.1%, October 4.3%. Busiest month is June at 24.2%.
1,950 verified observations of jellyfishes in Massachusetts, recorded across 12 months of the year on iNaturalist.
When jellyfishes are recorded in Massachusetts
Peak month
June
471 records (24.2% of the year)
| Month | Observations | Share |
|---|---|---|
| January | 4 | 0.2% |
| February | 6 | 0.3% |
| March | 52 | 2.7% |
| April | 227 | 11.6% |
| Maypeak | 419 | 21.5% |
| Junepeak | 471 | 24.2% |
| July | 207 | 10.6% |
| Augustpeak | 295 | 15.1% |
| September | 178 | 9.1% |
| October | 83 | 4.3% |
| November | 5 | 0.3% |
| December | 3 | 0.2% |
Jellyfishes you are most likely to see
| Species | Verified observations |
|---|---|
| Atlantic Lion's Mane Jelly | 610 |
| Common Moon Jelly | 174 |
| Bay Nettle | 169 |
| Atlantic Sea Nettle | 45 |
| Dwarf Lion's Mane Jelly | 32 |
| Mauve Stinger | 31 |
| Lion's Mane Jelly | 10 |
| Southern Moon Jelly | 8 |
In Massachusetts, September carries 9.1% of the year's jellyfishes sightings, about 0.8 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 is easing off from August (15.1%) into September, and it heads toward October (4.3%) after. The busiest month is June (24.2%), so if timing is flexible, that window is the safer bet.
The jellyfishes most often recorded in Massachusetts are Atlantic Lion's Mane Jelly, Common Moon Jelly and Bay 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
- Atlantic Lion's Mane Jelly610 records
- Common Moon Jelly174 records
- Bay Nettle169 records
- Atlantic Sea Nettle45 records
- Dwarf Lion's Mane Jelly32 records
- Mauve Stinger31 records
Plan your jellyfish trip in Massachusetts
Start with live tours near Appalachian National Scenic Trail, then compare a nearby stay and a broader wildlife backup before you lock in the trip.
GetYourGuide
Live tours nearbySee live tours near Appalachian National Scenic Trail
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 Appalachian National Scenic Trail
Compare hotels, cabins and lodges close to the best jellyfish viewing area in Massachusetts.
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Broader backupBook a jellyfish tour in Massachusetts
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 Massachusetts in September?+
Yes. September accounts for 178 of the 1,950 verified jellyfishes sightings logged in Massachusetts across the year, which is 9.1% of the annual total.
Is September a good time to see jellyfishes in Massachusetts?+
September is the 6th busiest month. It is workable, though June and May is the stronger window for a reliable sighting.
What month is best for jellyfishes in Massachusetts?+
June is the single busiest month, with the broader peak running through June, May and August, based on 1,950 verified observations.
Which jellyfishes are you most likely to see in Massachusetts?+
The most-recorded species in Massachusetts are Atlantic Lion's Mane Jelly, Common Moon Jelly and Bay Nettle, based on all-time iNaturalist counts.
See jellyfishes in Massachusetts in other months
More wildlife in Massachusetts