Month-specific sea-surface temperature · USA
Catalina Island Sea Temperature in July
20.3°C
68.5°F
In July, sea-surface temperature near Catalina Island has a historical monthly average of 20.3°C. This is not the reading for any particular holiday date.
Across 2023–2025, the lowest and highest yearly July monthly means were 19.5–21.1°C. These are not daily extremes.
Previous month
June · 18.8°C
Change into July: +1.5°C
Next month
August · 21.2°C
Change into next month: +0.9°C
Can you swim or snorkel in Catalina Island in July?
At 20.3°C our temperature-only guide describes the water as cool water. Comfort depends on your cold tolerance, immersion time and wind. A historical average cannot determine whether conditions are safe on any given day.
Do you need a wetsuit?
A 3 mm shorty or full wetsuit will make longer snorkels more comfortable.
Which beach should you choose?
Look for a beach sheltered from the actual forecast waves and wind on your visit. Exposure, currents and entry conditions vary even where water temperatures are similar. Follow local warnings.
Check the current waves, wind and snorkeling forecast →
A live forecast does not predict a future July. Check again close to your trip.
Waves and wind: recorded-model conditions for July
These figures come from a separately modelled, date-specific wind/wave backfill, not the NOAA SST series. A single observed season is not a climatological likelihood or a guarantee of safe conditions.
Compare nearby coasts with their own evidence
| Coast | Morning | Afternoon | Period |
|---|---|---|---|
| Dry Tortugas | 50% | 48% | Jul 2026 |
| Looe Key | 49% | 52% | Jul 2026 |
| Bahia Honda | 50% | 54% | Jul 2026 |
| Key Largo | 68% | 67% | Jul 2026 |
A “calm hour” meets fixed modelled wave/wind thresholds; neither visibility nor local currents, entry conditions or actual beach safety is measured here. Periods may differ by coast.
Nearby places in July
Comparable historical averages from independent marine grid cells. Warmer water does not imply safe snorkeling.
- La Jolla Cove 21.2°C
Data source and limitations
Source: Open-Meteo Marine API, MeteoFrance sea-surface temperature; 2023–2025. Marine model grid near 33.39, -118.42. Based on 3 yearly monthly means and 2232 recorded samples. Source methodology.
Modelled sea-surface temperatures do not establish underwater visibility, wildlife, calm currents or safe entry.