There is snow on the wind’s breath as we start down the trail towards the river.

The path is a dark wiggling line across the copper wash of the moorland that connects with the other thicker dark line of the River Brittle.

Above it, the Cuillin rise gigantic and toothy and elephant-skinned, the cracks and folds of its black gabbro rocks packed with snow. It makes me think of barnacle crusts, or old whales that have been scarred white by deep-sea battles with squid or slashed by ship propellers. There is something of the heaved-from-the-sea about this part of Skye. As if it is only a temporary breaching and that one day it will wake and shake and sink again.

A swimmer in the Fairy Pools, Glenbrittle on the Isle of Skye. PIC Jeff J Mitchell/Getty Images

James, Anna and I have driven across the island to swim at the fairy pools near Glenbrittle: a system of glacier-carved waterfalls where the pools are deep, clear and cold. Although it is only about 40 kilometres from the cottage we’re staying in – when the clouds rise we can see the Cuillin in the distance, bared like knuckles – the drive had taken over an hour as the roads narrowed and became slick with ice and snow. It is still early afternoon but as we head down the trail with our towels under our arms, most of the walkers appear to be heading in the opposite direction. James points at the clouds that seem to be lowering overhead. The sky has turned the colour of old ash.

The snow begins to fall as James and I are looking for ways down into one of the pools. Thick, fluffy, downy flakes. A feathery snow that furs our clothes and hangs on the black sides of the rock before disappearing, as if it is somehow worming its way inside. The pool is probably deep enough to plunge into, but I don’t want to risk it. The idea of submerging so quickly is not appealing. The water is calling, though. I don’t think I’ve ever seen natural water so strangely, ethereally blue. I know it is caused by reflections and light bouncing from mineral-rich rock, but still it holds a magic that fits with the snow. We find a narrow route down through rocks that are so cold they feel as if they will stick to the skin, and stand on a narrow ledge about a foot above the water. The river flows along a narrow corridor of rock before turning sharply into a deep pool that undercuts a cliff-like boulder. The water drops smoothly down to the pool below, creating a perfectly still infinity pool whose surface is dimpled only by the falling snow.

James is in first. I can see from the thinness of his lips that it is cold, how he is forcing himself to smile and keep going. I lower myself to the stone ledge, hold the rock overhang and the slab underneath me, my legs and arms in the water. I can feel the snow on my bare shoulders, on my chest. My skin is tightening to it. It doesn’t feel as cold as rain. Perhaps it is the gentleness of its landing instead of a stiletto-sharp pummelling. There is just a brush, a softness of a crystal wing.

I lower myself slowly, feeling the water reaching my nethers, rising over my stomach. It is so cold it feels scalding. Nerves scream in confusion, saying, whatever it is, you shouldn’t be in it. I dive forward and concentrate on my breathing – stretching out in a full stroke towards the end of the pool, where I can see the mountains are now disappearing in snow clouds. I pause at the lip of the pool, where it shelves up and my feet can touch the bottom. The snow is flying fast and if I raise my hand flakes will settle there. I think of the summer when we would lie on the ledge of the weir and see who could get a damselfly to alight on their fingers.

I shout out to James who is already out and drying and notice how my voice has been made strange and hoarse by the cold. I always sing to myself when I swim. It’s the way I can tell if I need to get out, the way certain letters get blunted. My ‘b’s stop working. I turn and swim back again, looking down to the bottom of the pool and think about trying to touch it, imagine how the water would feel around my head, the cold screwing in from the ears, pinching at the bridge of the nose. I picture too how the world would look through the blue lens of the water: the snow falling down towards the surface above me, as if I were driving with it flying at the windscreen. My legs and arms are slowing. The pool is sapping heat from me. It has just been minutes but it’s time to get out.

I dress, leaning my back against a rock. My teeth are chattering and I’m struggling to push my numb feet into my socks, but I can’t stop grinning, exhilarated by the intensity of the cold water.

Cold weather – the shorthand for that vast spectrum of conditions with the power to transform our world into something glimmering and magical – is generally seen as bad news for our mood and energy levels. The cold can lead to physical lethargy. A lack of sunlight can cause seasonal affective disorder. The human brain can confuse physical responses to chills with interpersonal feelings of coldness. We are more likely to feel listless, dispirited and unhappy in cold weather.

Then why am I not feeling that way? Why do I, red of face and cold of toe, enjoy the sensation of drawing in cold air, filling my lungs and, for just a moment, holding a scrap of that winter freeze in my chest? Why do I feel that each time I go into the cold and the ice there is something left in my blood and bones that makes the rest of that day feel more gentle, kinder, happier?

Maybe the answer is because so many of the reports on mood shifts and chemical changes are not actually based on an experience of snow, frost, ice or the sensation of supercooled water on skin. In fact, they are about almost the very opposite. According to Psychology Today, cold weather creates stress in the human body not because we are going out, but because we are staying in. Everyday activities are crimped because putting on extra layers is just too much bother. Perhaps it is our unwillingness to go outside in what we consider bad weather that is really damaging our moods.

Edited extract from In All Weathers: A Journey Through Rain, Fog, Wind, Ice and Everything In Between by Matt Gaw. Published by Elliott & Thompson in hardback at £16.99ENDS

A winter dip in Skye's Fairy Pools is a fantastic experience for writer Matt Gaw