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From winter to spring

You've been dipping through the winter. So, now that spring is on its way, how will you change your swimming habits?

Summer to winter is an easy transition. The water stays fairly warm in the autumn, tending to drop in temperature more slowly than the air and you gradually acclimatise to the colder water. You find that you naturally reduce the amount of time you spend swimming and increase the number of layers you put on afterwards.

Winter to summer isn't so simple. For a start, spring is unpredictable. One year there's snow, while same day the following year features strong winds. Or warm sun. Or heavy rain. Secondly, the water remains stubbornly frigid for a long time. That means that the daytime air temperature can climb well above the water temperature.

So, how do you transition from winter to spring? And if you've not been winter swimming, when can you start training for your summer event?

Managing the changing seasons

If you've been swimming through winter you're used to short dips in very cold temperatures. As the water temperature rises, you can start to increase the amount of time you spend swimming. You can also do more with your swimming like concentrating on technique, speed or distance rather than just thinking about how cold you are!

You know that you've earned your winter swimming stripes when twelve degrees feels warm. But think back to the autumn and how twelve degrees felt when you'd got used to swimming at 18C. Cold, wasn't it? It's important that you bear this in mind because, as I wrote before, it's very easy to get carried away and stay in for too long.

So, as you increase the time and distance that you spend in the water, be aware of your body. The same rules apply as in winter: don't stay in too long, get out while you're still in that comfortable zone, don't swim alone and warm up properly afterwards. Two minutes per degree of water temperature is a good rule of thumb, but you should pay attention to what your body's telling you.

Starting outdoor swimming

So many people ask me when they can start outdoor swimming. We're not quite there yet, but we're getting close. March is still very cold. And to the unacclimatised the cold water is not only a shock for your body, it also makes it hard to think properly while you're swimming.

I think that 12-14 degrees centigrade is the magic temperature. Technically it's still cold (by definition), but once you've got over that 90-120 second period of cold water shock, you are going to be comfortable for long enough to get in a decent swim. You will also be comfortable enough in your body to be able to use your brain.

While our climate is unpredictable, you can expect the water temperature to reach double digits in April, possibly the beginning of May. It's worth bearing in mind that the sea will warm up much more slowly than a smaller body of water such as a lake. River water close to source or at a high altitude will stay cold all year around.

What is cold water?

Finding out what classifies as cold water isn't easy, not least because it's fairly subjective. What classifies as cold for rescues is different to what's considered cold for swimming. You also have to take into account the air temperature: a big differential between air and water temperature will make cool water feel like an ice bath. Here's a rough guide:

  • >24C = very warm

  • 18-24C = warm

  • 12-18C = cool

  • 6-12C = cold

  • <6 = really cold

Here's an equation that accounts for air temperature, including wind chill. Cold water swimming is when: Air temp (feels like) + water temp = <20C

Start slowly and build

So, whether you've been swimming all winter or not, the guidelines are the same: start, or keep on, swimming for a short amount of time, listening to your body. As the water warms and you get more used, you can build up to longer distances and more time enjoying the water.


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