Sea Temperature in Čiovo Island in September (2026) – Swimming Guide
Sea temperature in Čiovo Island in September averages 25.1°C (typical range 22.8°C–27.2°C). Swimming conditions, 10-day trends, and top beaches.
Typical Range: 22.8°C – 27.2°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 6
Sea Temperature Progression in September by Decade
Multi-year oceanographic measurements across early, mid, and late month:
Annual Oceanographic Climatology for Čiovo Island
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 | 14°C (12.4° – 15.5°) | 13°C | 6.6°C | 5 h | 8 d | Crisp & cool |
| February | 13.2°C (11.6° – 14.6°) | 13.5°C | 6.9°C | 5.8 h | 7 d | Crisp & cool |
| March | 14.2°C (12.6° – 15.8°) | 16.1°C | 9.1°C | 7 h | 7 d | Crisp & cool |
| April | 16.4°C (14.8° – 18.6°) | 19.7°C | 12.2°C | 8.5 h | 7 d | Crisp & cool |
| May → | 20°C (17.8° – 22.5°) | 24.4°C | 16.5°C | 10 h | 5 d | Refreshing & invigorating |
| June → | 24.1°C (21.5° – 26.8°) | 28.7°C | 20.3°C | 11.5 h | 4 d | Comfortable & warm |
| July → | 26.4°C (24.5° – 28.8°) | 31.7°C | 23.1°C | 12.5 h | 2 d | Very warm & ideal |
| August → | 27.4°C (25.4° – 29.8°) | 31.6°C | 22.9°C | 11.8 h | 2 d | Very warm & ideal |
| September → | 25.1°C (22.8° – 27.2°) | 26.7°C | 18.7°C | 9.4 h | 4 d | Very warm & ideal |
| October → | 21.7°C (19.6° – 24°) | 21.8°C | 14.9°C | 7.2 h | 7 d | Comfortable & warm |
| November | 18°C (16° – 19.8°) | 17°C | 10.6°C | 5.2 h | 9 d | Refreshing & invigorating |
| December | 15.2°C (13.5° – 16.8°) | 13.6°C | 7.5°C | 4.4 h | 8 d | Crisp & cool |
Top Rated Beaches in Čiovo Island for this Season
Curated bathing spots featuring verified water cleanliness and supreme swimming comfort (11 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 Čiovo Island
Is it warm enough to swim in Čiovo Island in September?
In September, average sea temperature in Čiovo Island is 25.1°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 September?
Average daytime air temperature reaches 26.7°C (18.7°C at night), featuring approximately 9.4 hours of bright sunshine daily and only 4 rainy days.
How does sea temperature evolve from early to late September?
During early September (1st–10th) water averages 26°C, mid-month (11th–20th) sits at 25.1°C, and late month (21st–31st) reaches 24.2°C.