Best Time to See Jellyfishes in Oregon
August, September and July is the best time to see jellyfishes in Oregon. Based on 3,455 verified iNaturalist observations, here is exactly when jellyfishes are most active across the year in Oregon.
By Tim, founder of Easy Street Markets. I maintain the wildlife database and verify every animal and source myself. Updated July 2, 2026.
Pacific Lion's Mane Jelly · Lynn CC BY
Pacific Sea Nettle · Michele Jones CC BY
Pacific Lion's Mane Jelly · Lee Cain CC BY
3,455 verified observations of jellyfishes in Oregon, recorded across 12 months of the year on iNaturalist.
When jellyfishes are recorded in Oregon
Peak month
August
935 records (27.1% of the year)
| Month | Observations | Share |
|---|---|---|
| January | 111 | 3.2% |
| February | 98 | 2.8% |
| March | 54 | 1.6% |
| April | 25 | 0.7% |
| May | 66 | 1.9% |
| June | 228 | 6.6% |
| Julypeak | 478 | 13.8% |
| Augustpeak | 935 | 27.1% |
| Septemberpeak | 798 | 23.1% |
| October | 373 | 10.8% |
| November | 173 | 5% |
| December | 116 | 3.4% |
Jellyfishes you are most likely to see
| Species | Verified observations |
|---|---|
| Pacific Sea Nettle | 1,217 |
| Greater Moon Jelly | 856 |
| Pacific Lion's Mane Jelly | 786 |
| Egg-yolk Jelly | 116 |
| Purple-striped Sea Nettle | 9 |
| Barrel Jellies | 1 |
Weather to expect, source Open-Meteo
Typical weather in Oregon
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 47 to 83 degrees Fahrenheit, so pack for that.
| Month | Avg high | Avg low | Rain |
|---|---|---|---|
| Jan | 39°F | 26°F | 2" |
| Feb | 38°F | 22°F | 2.4" |
| Mar | 43°F | 25°F | 1.9" |
| Apr | 52°F | 32°F | 2.2" |
| May | 61°F | 40°F | 2" |
| Jun | 71°F | 48°F | 1.1" |
| Julbest time | 83°F | 56°F | 0.1" |
| Augbest time | 81°F | 56°F | 0.4" |
| Sepbest time | 71°F | 47°F | 1.2" |
| Oct | 58°F | 37°F | 1.2" |
| Nov | 45°F | 28°F | 2.3" |
| Dec | 37°F | 25°F | 2.4" |
Typical recent conditions (5-year means) from the Open-Meteo archive, averaged for Oregon. Weather varies year to year, so treat these as a guide.
Sightings of jellyfishes in Oregon peak in August, when 935 of the year's 3,455 verified observations are logged — about 27.1% of the annual total. Activity stays high through August, September and July.
The quietest stretch is April, when jellyfishes are hardest to find — April sees just 25 records. If a reliable sighting matters, plan around the peak window rather than the off-season.
The jellyfishes you are most likely to encounter in Oregon are Pacific Sea Nettle, Greater Moon Jelly and Pacific Lion's Mane 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 Oregon
- Crater Lake National Park — National Park
- Fort Vancouver National Historic Site — National Historic Site
- Lewis & Clark National Historic Trail — National Historic Trail
- Lewis and Clark National Historical Park — National Historical Park
- Nez Perce National Historical Park — National Historical Park
- Oregon Caves National Monument & Preserve — National Monument & Preserve
Frequently asked questions
What is the best month to see jellyfishes in Oregon?+
August is the single best month, and the broader peak window runs through August, September and July, based on 3,455 verified iNaturalist observations.
When are jellyfishes hardest to see in Oregon?+
April is the quietest month for jellyfishes in Oregon, with only 25 verified records.
Are jellyfishes active year-round in Oregon?+
Jellyfishes are recorded in 12 of 12 months in Oregon, so they can be seen year-round, with a clear peak in August.
More places to see jellyfishes
More wildlife in Oregon