Editing Houtman Abrolhos (section)

===Temperature and salinity===
[[File:Houtman Abrolhos sea temperature and salinity.png|thumb|Mean monthly temperature versus [[salinity]] for the Houtman Abrolhos and the adjacent coast in 1994, showing the Houtman Abrolhos to be much less variable.]]

Sea temperature at the islands varies according to a diurnal cycle, with the water at its coldest between six and eight in the morning, and at its warmest between three and four in the afternoon. In summer the daily temperature range is around 1&nbsp;°C (2&nbsp;°F); in winter it is about half that.<ref name="Pearce 1997"/>

There is also an annual cycle, with sea temperature varying by a little less than 4&nbsp;°C (7&nbsp;°F) over the year, peaking at nearly 24&nbsp;°C (75&nbsp;°F) in March, and falling to around 20&nbsp;°C (68&nbsp;°F) in September. This variability is much less than in nearby coastal waters, which reaches a similar peak in summer but drops as low as 18&nbsp;°C (64&nbsp;°F) in winter. The relatively low variability in sea temperatures at the Abrolhos is largely attributable to the Leeuwin Current, which bathes the islands in warm tropical water during winter months.<ref name="Pearce 1997"/>

A similar annual pattern occurs in [[salinity]]. There is a clear seasonal variation, with values ranging from a summer high of around 35.7 [[parts per trillion|ppt]], to a winter low of around 35.4 ppt. As with water temperatures, the variability in salinity is much smaller than in coastal waters, where summer salinity reaches 36.4 ppt. This difference is partly due to the low-salinity waters of the Leeuwin Current, but there are a number of other factors involved, including high evaporation of coastal waters in summer.<ref name="Pearce 1997"/>

Temperatures can also vary substantially from year to year. Annual mean temperatures vary by as much as 1&nbsp;°C (2&nbsp;°F); with cooler years usually cooler throughout the year. There is evidence that annual mean temperatures are related to [[El Niño-Southern Oscillation]] events.<ref name="Pearce 1997"/>

The [[water column]] is generally well-mixed, with no evidence of a significant [[halocline]] or [[thermocline]]. Mean differences in water temperature between sea surface and sea bed range from only half a degree (Celsius; 1&nbsp;°F) in summer to almost zero in winter, and differences in salinity are very small even when the Leeuwin Current is at its strongest.<ref name="Pearce 1997"/>