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If the air is cooler than the sea, should you swim to warm up?

Ben Domensino, Tuesday May 15, 2018 - 13:22 AEST

Autumn is an interesting time of year in Australia because in many parts of the country, the air temperature is lower than the water temperature.

This difference occurs because water retains heat better than air does, causing it to cool down slower than the air as we descend towards winter.

This lag in ocean cooling means that during autumn and early winter, it's often colder out of the water than in for many coastal locations around the southern half of Australia.

For example, the air temperature in Sydney this morning was 11 degrees at 7am, while the sea surface temperature measured off the coast was 19 degrees.

In Melbourne, this morning's 17 degrees in Port Phillip Bay was nearly twice as warm as the city's nine degree air temperature shortly after 9am.

Before you go jumping in the water to warm up though, there are a couple of other things to consider.

Firstly, water is better at extracting heat from your body than air because it is a better thermal conductor. So, even if it's a bit warmer in the water than out, your body will lose heat faster in the ocean.

Secondly, you'll have to get out of the water eventually. When you do, your wet skin will be exposed to the wind and evaporative cooling will make it feel even colder than it was before you got in.

If you have to be outside, the best way to stay warm is to layer up. Your clothes trap warm air near your skin and prevent the wind from blowing it away.

If you must swim, wear a wetsuit. These neoprene shells trap a little bit of water near your skin, where it warms up and acts like an insulator.

- Weatherzone

© Weatherzone 2018

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