For the east coast, persistent northeast winds tend to move the upper layer of ocean toward the east. Warming surface water replaces the rise of colder water from beneath which they feel cold for those who are swimming at sea.
The return effect – a drop that brings warmer, more tropical waters from Eastern Australia – typically follows persistent southern winds.
"The last true south end passed on weekends before Christmas," said Mr. Hopkins, adding that since then there are stable northeastern winds and lows.
"Headache of ice cream"
A spokeswoman for the Australian Coastal Party said that beachbeds can often be caught outside the guard when the hot air temperatures that attract people do not coincide when people swing.
"These are the times when [the cool water temperatures] are more noticeable, "he said, allowing some to experience" headache of ice cream "from sudden cold.
Jordan Notar, a meteorological bureau official, said the next South Change is not expected to reach Sydney by Sunday.
"It will obviously reduce the air temperature," he said.
Before that, however, Sydney Wizards should have enough reason to think about traveling to the beach, especially on Friday and Saturday, when the maximum is 31 and 33 degrees. The western suburbs should see again how alive it climbs in the tall 30's.
"At present, the power of the northwestern countries will resist or delay that sea breeze [on Saturday]Said Mr. Notar.
Upwelling cold water has another consequence: an increased chance of getting seagrass, while warm humid air moves over colder seas.
South East Australia will endure some of the most intense heat in the region on Friday. "It looks like the middle of the 40s through the river and the lower and upper western parts," he said.
Victoria may have a record 47.2 degrees record in January, while Melbourne is expected to bake in 42 degrees heat.
While coastal waters along the coast of Sydney may seem to be on the cold side, the same is true for most of the Tasmanian Sea.
The sea surface temperature for this time of year is several degrees above normal, according to the US National Oceanic Administration and the Atmosphere.
Peter Hannam is the environmental editor at Sydney Morning Herald. It covers broad environmental issues, from climate change to renewable energy sources to Fairfax Media.