Sea Temperature in Opatija in August (2026) – Swimming Guide
Sea temperature in Opatija in August averages 25.6°C (typical range 23.6°C–28°C). Swimming conditions, 10-day trends, and top beaches.
Typical Range: 23.6°C – 28°C
Standard swimwear. No wetsuit needed; water is warm and welcoming even for infants.
Povoljni termički uvjeti za cjelodnevni boravak uz more
4 rainy days · UV Index 8
Sea Temperature Progression in August by Decade
Multi-year oceanographic measurements across early, mid, and late month:
Annual Oceanographic Climatology for Opatija
Multi-year historical records by the Croatian Meteorological and Hydrological Service (DHMZ) & Institute of Oceanography and Fisheries (IZOR)
| Month | Sea Temperature | Day Air | Night Air | Sun Hours | Rain Days | Swimming Verdict |
|---|---|---|---|---|---|---|
| January | 12°C (10.2° – 13.6°) | 10.1°C | 4°C | 4.2 h | 7 d | Crisp & cool |
| February | 11.3°C (9.6° – 12.8°) | 11°C | 4.4°C | 5.1 h | 6 d | Crisp & cool |
| March | 12.6°C (11° – 14.3°) | 14.1°C | 7.1°C | 6.4 h | 7 d | Crisp & cool |
| April | 15°C (13.3° – 17.3°) | 18°C | 10.4°C | 7.8 h | 8 d | Crisp & cool |
| May → | 18.4°C (16° – 20.8°) | 22.7°C | 14.7°C | 9.2 h | 7 d | Refreshing & invigorating |
| June → | 22.6°C (19.6° – 25.2°) | 26.8°C | 18.5°C | 10.5 h | 6 d | Comfortable & warm |
| July → | 25.2°C (23° – 27.6°) | 29.7°C | 21.1°C | 11.8 h | 4 d | Very warm & ideal |
| August → | 25.6°C (23.6° – 28°) | 29.5°C | 20.9°C | 11 h | 4 d | Very warm & ideal |
| September → | 22.9°C (20.6° – 25°) | 24.7°C | 17°C | 8.6 h | 6 d | Comfortable & warm |
| October → | 19.2°C (17° – 21.6°) | 19.5°C | 12.9°C | 6.2 h | 8 d | Refreshing & invigorating |
| November | 16.3°C (14.4° – 18°) | 14.8°C | 8.7°C | 4.5 h | 9 d | Crisp & cool |
| December | 13.6°C (11.8° – 15°) | 10.9°C | 5.1°C | 3.8 h | 8 d | Crisp & cool |
Top Rated Beaches in Opatija for this Season
Curated bathing spots featuring verified water cleanliness and supreme swimming comfort (25 verified locations):
Expert Swimming & Marine Tips
🌬️ Winds & Marine Currents
Summer afternoons regularly welcome the refreshing Maestral (NW) sea breeze. A strong Bura (NE) wind can temporarily drop surface water temperatures by 1–2°C, especially in shallow coastal coves.
☀️ Sun Protection & UV Exposure
In peak summer months, the UV index regularly surpasses 8. Limit unprotected sunbathing between 11:00 AM and 4:00 PM, and always use high-factor water-resistant sunscreen.
🤿 Water Clarity & Sea Urchins
The Adriatic Sea here consistently scores excellent water quality under EU bathing water directives. Sea urchins on rocky shallows serve as nature’s bio-indicator of immaculate water purity.
Frequently Asked Questions – Sea Temperature in Opatija
Is it warm enough to swim in Opatija in August?
In August, average sea temperature in Opatija is 25.6°C. Very warm & ideal / Perfect for long swims & kids. Standard swimwear. No wetsuit needed; water is warm and welcoming even for infants.
What is the air temperature and daily sunshine in August?
Average daytime air temperature reaches 29.5°C (20.9°C at night), featuring approximately 11 hours of bright sunshine daily and only 4 rainy days.
How does sea temperature evolve from early to late August?
During early August (1st–10th) water averages 26.5°C, mid-month (11th–20th) sits at 25.6°C, and late month (21st–31st) reaches 24.7°C.