It’s Alright, Once You’re In

By Dan Hutton on December 15, 2010 in

?As we all know, it has been an extremely wet spring/summer with many cold, bleak days. In between that, there have been some patchy stretches of baking hot days. I remember one such day early last month when I needed to cool off. I ran headlong into the surf and was met with instant brain-freeze and hyperventilation. The water was a mere 16 degrees – half of what the air temperature was that day!

So why was it so cold? In practical terms, sea temperature refers to surface temperatures (SST). This refers to the top millimeter layer (if measured by satellites) or top meter layer (if measured by a buoy) of water. Generally speaking, the deeper you go, the colder it gets. Latitude comes into the equation as well – the closer to the equator, the warmer the SST will be. Since the 80s, satellites have been used to measure SST and have provided us with a holistic understanding of how the changing SST works, complete with thermo-coloured imagery.

The Sydney coast is influenced by the East Australian Current (ridden ‘bodaciously’ by the Finding Nemo turtles), which brings warm water down from the Coral Sea. Earlier in December when the average air temperature is fair, the water is colder, but by Christmas the water is usually much more comfortable to swim in. Then, when Autumn comes around, the air temperature gets cooler but the water stays warm. 

We have all felt micro-temperatures whilst swimming at the beach with warm and cold patches. Just remember that swimming through a warm patch may not always be due to sea temp – especially if there are kids around!

?Did You Know?

Unlike fresh water, which freezes at 0 degrees Celsius, sea water actually freezes at -1.94 degrees Celsius. 

?January Willy Weather Statistics

?TEMPERATURE?

High – 45.3 (1939)
Low – 10.6 (1949)
Average – 22.3

?RAINFALL?

High – 387.1mm (1911)
Low – 5.6mm (1985)
Average – 102mm

?MOONPHASES

New moon – 4th January
First quarter – 12th January
Full moon – 19th January
Last quarter – 26th January

SUNRISE

January 1st:
Rise – 5:47 am
Set – 8:09 pm

January 31st:
Rise – 6:15 am
Set – 8:01 pm