Month-specific sea-surface temperature · Australia

Cairns Sea Temperature in September

24.8°C

76.6°F

In September, sea-surface temperature near Cairns has a historical monthly average of 24.8°C. This is not the reading for any particular holiday date.

Across 2023–2025, the lowest and highest yearly September monthly means were 24.4–25.3°C. These are not daily extremes.

Previous month

August · 23.6°C

Change into September: +1.2°C

Next month

October · 26.8°C

Change into next month: +2.0°C

Can you swim or snorkel in Cairns in September?

At 24.8°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.

Cairns is a mainland gateway. Reef water a short boat ride east can differ from Trinity Inlet. Use the monthly profile as a regional guide, then check Green Island, Fitzroy Island or an outer-reef forecast for the water you will enter.

Check the current waves, wind and snorkeling forecast →

A live forecast does not predict a future September. Check again close to your trip.

Nearby places in September

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

Data source and limitations

Source: Open-Meteo Marine API, MeteoFrance sea-surface temperature; 2023–2025. Marine model grid near -16.92, 145.77. 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.