Jellyfishes in Delaware in September
Yes, September is one of the best months to see jellyfishes in Delaware. It is the 3rd busiest month of the year, with 55 of the 568 sightings logged across the year (9.7%), 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 Delaware
9.7%
of yearly sightings
55
records in September
#3
busiest month of 12
568
verified records a year
August 27.1%, September 9.7%, October 7.4%. Busiest month is July at 33.1%.
568 verified observations of jellyfishes in Delaware, recorded across 12 months of the year on iNaturalist.
When jellyfishes are recorded in Delaware
Peak month
July
188 records (33.1% of the year)
| Month | Observations | Share |
|---|---|---|
| January | 7 | 1.2% |
| February | 6 | 1.1% |
| March | 5 | 0.9% |
| April | 11 | 1.9% |
| May | 3 | 0.5% |
| June | 40 | 7% |
| Julypeak | 188 | 33.1% |
| Augustpeak | 154 | 27.1% |
| Septemberpeak | 55 | 9.7% |
| October | 42 | 7.4% |
| November | 34 | 6% |
| December | 23 | 4% |
Jellyfishes you are most likely to see
| Species | Verified observations |
|---|---|
| Bay Nettle | 104 |
| Dwarf Lion's Mane Jelly | 78 |
| Mushroom Jelly | 45 |
| Common Moon Jelly | 32 |
| Southern Moon Jelly | 31 |
| Cannonball Jelly | 23 |
| Atlantic Sea Nettle | 22 |
| Atlantic Lion's Mane Jelly | 5 |
In Delaware, September carries 9.7% of the year's jellyfishes sightings, about 1.4 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 (27.1%) into September, and it heads toward October (7.4%) 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 Delaware are Bay Nettle, Dwarf Lion's Mane Jelly and Mushroom Jelly. 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
- Bay Nettle104 records
- Dwarf Lion's Mane Jelly78 records
- Mushroom Jelly45 records
- Common Moon Jelly32 records
- Southern Moon Jelly31 records
- Cannonball Jelly23 records
Plan your jellyfish trip in Delaware
Start with live tours near Captain John Smith Chesapeake National Historic Trail, then compare a nearby stay and a broader wildlife backup before you lock in the trip.
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Live tours nearbySee live tours near Captain John Smith Chesapeake National Historic 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 Captain John Smith Chesapeake National Historic Trail
Compare hotels, cabins and lodges close to the best jellyfish viewing area in Delaware.
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Broader backupBook a jellyfish tour in Delaware
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Frequently asked questions
Can you see jellyfishes in Delaware in September?+
Yes. September accounts for 55 of the 568 verified jellyfishes sightings logged in Delaware across the year, which is 9.7% of the annual total.
Is September a good time to see jellyfishes in Delaware?+
September is one of the best months. It ranks 3rd of the year and sits inside the peak window of July, August and September.
What month is best for jellyfishes in Delaware?+
July is the single busiest month, with the broader peak running through July, August and September, based on 568 verified observations.
Which jellyfishes are you most likely to see in Delaware?+
The most-recorded species in Delaware are Bay Nettle, Dwarf Lion's Mane Jelly and Mushroom Jelly, based on all-time iNaturalist counts.
See jellyfishes in Delaware in other months
More places to see jellyfishes
More wildlife in Delaware