Month-specific sea-surface temperature · Australia

Great Barrier Reef Sea Temperature in September

24.7°C

76.5°F

In September, sea-surface temperature near Great Barrier Reef has a historical monthly average of 24.7°C. This is not the reading for any particular holiday date.

Across 2023–2025, the lowest and highest yearly September monthly means were 24.3–25.2°C. These are not daily extremes.

Previous month

August · 23.6°C

Change into September: +1.1°C

Next month

October · 26.3°C

Change into next month: +1.6°C

Can you swim or snorkel in Great Barrier Reef in September?

At 24.7°C our temperature-only guide describes the water as mild 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 rash guard is useful; cold-sensitive snorkelers may prefer a shorty wetsuit.

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 September. Check again close to your trip.

Waves and wind: recorded-model conditions for September

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.

Morning calm hours

Afternoon calm hours

Historical coverage

September 2026

30 valid days

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 September

Comparable historical averages from independent marine grid cells. Warmer water does not imply safe snorkeling.

Low Isles 24.8°C
Agincourt Reef 25.4°C
Port Douglas 24.8°C
Hastings Reef 25.1°C
Michaelmas Cay 24.7°C
Moore Reef 25.2°C

Great Barrier Reef Sea Temperature: All 12 Months

Choose a month for available historical evidence, month comparisons and swim guidance. Missing history is clearly marked and never presented as a long-term normal.

January 29.9°C February 29.5°C March 29.1°C April 28.3°C May 25.9°C June 24.6°C July 24.0°C August 23.6°C September 24.7°C October 26.3°C November 28.0°C December 29.0°C

Data source and limitations

Source: Open-Meteo Marine API, MeteoFrance sea-surface temperature; 2023–2025. Marine model grid near -16.29, 145.70. Based on 3 yearly monthly means and 2160 recorded samples. Source methodology.

Modelled sea-surface temperatures do not establish underwater visibility, wildlife, calm currents or safe entry.