Best Time to See Jellyfishes in Maine
June, July and August is the best time to see jellyfishes in Maine. Based on 1,301 verified iNaturalist observations, here is exactly when jellyfishes are most active across the year in Maine.
By Tim, founder of Easy Street Markets. I maintain the wildlife database and verify every animal and source myself. Updated June 28, 2026.
Atlantic Lion's Mane Jelly · Public domain CC0
Lion's Mane Jellies · Michael CC BY
Atlantic Lion's Mane Jelly · Eric Baratta CC BY
1,301 verified observations of jellyfishes in Maine, recorded across 11 months of the year on iNaturalist.
When jellyfishes are recorded in Maine
Peak month
June
458 records (35.2% of the year)
| Month | Observations | Share |
|---|---|---|
| January | 5 | 0.4% |
| February | 3 | 0.2% |
| March | 11 | 0.8% |
| April | 12 | 0.9% |
| May | 91 | 7% |
| Junepeak | 458 | 35.2% |
| Julypeak | 454 | 34.9% |
| Augustpeak | 237 | 18.2% |
| September | 27 | 2.1% |
| October | 2 | 0.2% |
| November | 0 | 0% |
| December | 1 | 0.1% |
Jellyfishes you are most likely to see
| Species | Verified observations |
|---|---|
| Atlantic Lion's Mane Jelly | 207 |
| Lion's Mane Jelly | 184 |
| Common Moon Jelly | 120 |
| Egg-yolk Jelly | 5 |
| Dwarf Lion's Mane Jelly | 5 |
| Atlantic Sea Nettle | 1 |
| Greater Moon Jelly | 1 |
| Mauve Stinger | 1 |
Weather to expect, source Open-Meteo
Typical weather in Maine
Recent typical conditions by month, so you can plan a trip around both when jellyfishes are active and what the weather is doing. The best months to look for jellyfishes sit around 54 to 80 degrees Fahrenheit, so pack for that.
| Month | Avg high | Avg low | Rain |
|---|---|---|---|
| Jan | 28°F | 11°F | 4" |
| Feb | 28°F | 11°F | 3.1" |
| Mar | 39°F | 20°F | 2.7" |
| Apr | 51°F | 32°F | 4.8" |
| May | 64°F | 43°F | 3.2" |
| Junbest time | 74°F | 54°F | 3.7" |
| Julbest time | 80°F | 62°F | 4.9" |
| Augbest time | 77°F | 60°F | 4.7" |
| Sep | 69°F | 53°F | 4.4" |
| Oct | 58°F | 43°F | 5.3" |
| Nov | 43°F | 29°F | 3.8" |
| Dec | 34°F | 20°F | 5" |
Typical recent conditions (5-year means) from the Open-Meteo archive, averaged for Maine. Weather varies year to year, so treat these as a guide.
Sightings of jellyfishes in Maine peak in June, when 458 of the year's 1,301 verified observations are logged — about 35.2% of the annual total. Activity stays high through June, July and August.
The quietest stretch is November and December, when jellyfishes are hardest to find — no verified records exist for November. If a reliable sighting matters, plan around the peak window rather than the off-season.
The jellyfishes you are most likely to encounter in Maine are Atlantic Lion's Mane Jelly, Lion's Mane Jelly and Common Moon Jelly — the most-recorded species in the state. Each keeps its own seasonal rhythm, but the month-by-month pattern above reflects every reported sighting together.
Where to go
Best places to see jellyfishes in Maine
- Acadia National Park — National Park
- Appalachian National Scenic Trail — National Scenic Trail
- Katahdin Woods and Waters National Monument — National Monument
- Saint Croix Island International Historic Site — International Historic Site
- Frances Perkins National Monument — National Monument
- Maine Acadian Culture
Frequently asked questions
What is the best month to see jellyfishes in Maine?+
June is the single best month, and the broader peak window runs through June, July and August, based on 1,301 verified iNaturalist observations.
When are jellyfishes hardest to see in Maine?+
November is the quietest month for jellyfishes in Maine, with no verified records on iNaturalist.
Are jellyfishes active year-round in Maine?+
Jellyfishes are recorded in 11 of 12 months in Maine, so they can be seen year-round, with a clear peak in June.
More places to see jellyfishes
More wildlife in Maine