Best Time to See Jellyfishes in California
August, July and September is the best time to see jellyfishes in California. Based on 8,243 verified iNaturalist observations, here is exactly when jellyfishes are most active across the year in California.
By Tim, founder of Easy Street Markets. I maintain the wildlife database and verify every animal and source myself. Updated June 28, 2026.
Black Jelly · Michael Bear CC BY
Australian Spotted Jelly · Millie Basden CC BY
Egg-yolk Jelly · Michael Bear CC BY
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 |
Weather to expect, source Open-Meteo
Typical weather in California
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 57 to 94 degrees Fahrenheit, so pack for that.
| Month | Avg high | Avg low | Rain |
|---|---|---|---|
| Jan | 53°F | 31°F | 5.6" |
| Feb | 53°F | 30°F | 4.4" |
| Mar | 55°F | 33°F | 7.3" |
| Apr | 66°F | 40°F | 1.8" |
| May | 73°F | 46°F | 1.6" |
| Jun | 84°F | 55°F | 0.2" |
| Julbest time | 94°F | 62°F | 0" |
| Augbest time | 93°F | 62°F | 0.3" |
| Sepbest time | 85°F | 57°F | 0.8" |
| Oct | 73°F | 46°F | 1.2" |
| Nov | 61°F | 36°F | 2.3" |
| Dec | 53°F | 33°F | 7.8" |
Typical recent conditions (5-year means) from the Open-Meteo archive, averaged for California. Weather varies year to year, so treat these as a guide.
Sightings of jellyfishes in California peak in August, when 1,300 of the year's 8,243 verified observations are logged — about 15.8% of the annual total. Activity stays high through August, July and September.
The quietest stretch is January, February and March, when jellyfishes are hardest to find — January sees just 314 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 California are Greater Moon Jelly, Pacific Sea Nettle and Purple-striped Sea Nettle — 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 California
- Alcatraz Island
- Cabrillo National Monument — National Monument
- Channel Islands National Park — National Park
- Death Valley National Park — National Park
- Devils Postpile National Monument — National Monument
- Golden Gate National Recreation Area — National Recreation Area
Frequently asked questions
What is the best month to see jellyfishes in California?+
August is the single best month, and the broader peak window runs through August, July and September, based on 8,243 verified iNaturalist observations.
When are jellyfishes hardest to see in California?+
January is the quietest month for jellyfishes in California, with only 314 verified records.
Are jellyfishes active year-round in California?+
Jellyfishes are recorded in 12 of 12 months in California, so they can be seen year-round, with a clear peak in August.
More places to see jellyfishes
More wildlife in California