NOAA SATELLITE DATA (1991–2020 30-YEAR CLIMATOLOGY)

Belgium Sea Temperature in September

Historical 30-year sea surface temperatures across 4 coastlines in Belgium for September. Derived from NOAA 0.25° blended satellite and in-situ marine observations.

Climatology Notice: Temperatures represent the 30-year long-term historical average (1991–2020 normal), not a live single-day sensor forecast.

17.1°C

Bracing / Crispaverage across 4 surveyed coastlines in Belgium, September

Ranges 15.8°C at Knokke-Heist Beach (Het Zoute) to 17.5°C at De Haan Beach.
No coastline in Belgium reaches 21°C in any month — this is wetsuit or cold-water swimming.
1.6°C cooler than Belgium’s August peak of 18.7°C (see August).

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The September Thermal Lag Advantage

Because seawater has a high specific heat capacity, it acts as a massive thermal battery. Southern European and Mediterranean basins absorb solar energy all summer, reaching maximum heat storage by late August. In September, while air temperatures drop, the water releases heat slowly, which creates sea temperatures that are typically 3°C to 5°C warmer than in June.

CYPRUS (AYIA NAPA / PROTARAS)

27.5°C

Effortless swimming

TURKEY (ANTALYA / KAŞ)

27.3°C

Warm bathwater

GREECE (CRETE / RHODES)

25.4°C

Extended season

MALTA & GOZO

26.1°C

Crystal clear