Water temperature of the South China Sea in september Where to swim in the South China Sea in september 2025?

Several countries border the seaside of the South China Sea, including: Borneo (Kalimantan), Brunei, Cambodia, China, Hong Kong, Malaysia, Palawan island, Philippines, Singapore and Sumatra. We measure the water temperature daily in these countries and archive it in order to calculate monthly averages, like those of the month of september.

The seasonal average for the water temperature in the month of september is between 81°F and 86°F. The lowest sea temperature measured this month is 78°F and the highest is 89°F.

The sea temperature map of the South China Sea in september

The map below presents a monthly average of the water temperature of the South China Sea for the month of september for several coastal cities. You can zoom and move around on the map. By clicking on the markers, you can see sea temperature details by city in september.