Sea Temperature in Lošinj Island in September (2026) – Swimming Guide
Sea temperature in Lošinj Island in September averages 23.5°C (typical range 21.2°C–25.6°C). Swimming conditions, 10-day trends, and top beaches.
Typical Range: 21.2°C – 25.6°C
Standard swimwear. Great for 30–60 minute continuous swims without any chill.
Povoljni termički uvjeti za cjelodnevni boravak uz more
6 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 Lošinj 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 | 12°C (10.2° – 13.6°) | 10.2°C | 4.1°C | 4.2 h | 7 d | Crisp & cool |
| February | 11.3°C (9.6° – 12.8°) | 11.1°C | 4.5°C | 5.1 h | 6 d | Crisp & cool |
| March | 12.6°C (11° – 14.3°) | 14.2°C | 7.2°C | 6.4 h | 7 d | Crisp & cool |
| April | 15°C (13.3° – 17.3°) | 18.1°C | 10.5°C | 7.8 h | 8 d | Crisp & cool |
| May → | 18.4°C (16° – 20.8°) | 22.8°C | 14.8°C | 9.2 h | 7 d | Refreshing & invigorating |
| June → | 22.6°C (19.6° – 25.2°) | 26.9°C | 18.6°C | 10.5 h | 6 d | Comfortable & warm |
| July → | 25.2°C (23° – 27.6°) | 29.8°C | 21.2°C | 11.8 h | 4 d | Very warm & ideal |
| August → | 26.2°C (24.2° – 28.6°) | 29.6°C | 21°C | 11 h | 4 d | Very warm & ideal |
| September → | 23.5°C (21.2° – 25.6°) | 24.8°C | 17.1°C | 8.6 h | 6 d | Comfortable & warm |
| October → | 19.8°C (17.6° – 22.2°) | 19.6°C | 13°C | 6.2 h | 8 d | Refreshing & invigorating |
| November | 16.3°C (14.4° – 18°) | 14.9°C | 8.8°C | 4.5 h | 9 d | Crisp & cool |
| December | 13.6°C (11.8° – 15°) | 11°C | 5.2°C | 3.8 h | 8 d | Crisp & cool |
Top Rated Beaches in Lošinj Island for this Season
Curated bathing spots featuring verified water cleanliness and supreme swimming comfort (34 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 Lošinj Island
Is it warm enough to swim in Lošinj Island in September?
In September, average sea temperature in Lošinj Island is 23.5°C. Comfortable & warm / Recommended for all swimmers. Standard swimwear. Great for 30–60 minute continuous swims without any chill.
What is the air temperature and daily sunshine in September?
Average daytime air temperature reaches 24.8°C (17.1°C at night), featuring approximately 8.6 hours of bright sunshine daily and only 6 rainy days.
How does sea temperature evolve from early to late September?
During early September (1st–10th) water averages 24.4°C, mid-month (11th–20th) sits at 23.5°C, and late month (21st–31st) reaches 22.6°C.