Changes in ocean temperature are of immense importance for global climate studies, marine ecology and fish recruitment, as well as being of interest to recreational swimmers. Because of the Leeuwin Current, water temperatures off Western Australia are some 4°C warmer than those at corresponding latitudes off the west coasts of southern Africa and South America. Water temperature measurements along the Western Australian coast are relatively sparse, although some intensive studies have been undertaken near cities and regional centres, as well as at selected sites important for fisheries.

Measurements off the west coast between Shark Bay and Cape Leeuwin have shown that the overall along-shore temperature gradient is about 0.5°C per degree of latitude (about 100 km), and that there is a seasonally-reversing temperature gradient across the continental shelf. In summer, shallow near-coastal waters warm because of heat input from the sun and the atmosphere, so the temperature falls slightly with distance offshore. In winter, on the other hand, coastal waters cool rapidly because of heat loss to the atmosphere, and at the same time the Leeuwin Current is maintaining warm conditions offshore, so there can be a large increase in surface temperature (say 4°C) between the coast and the edge of the continental shelf.

Monthly temperature statistics have been compiled for a number of sites along the west coast, using a variety of data sources. To see the monthly average temperature and minimum and maximum recorded at any site, click on the appropriate place in the adjacent chart.

Collaboration

• CSIRO Marine Research, Hobart
• Fisheries WA, Perth