Snowdonia in winter is not the same hill with colder air. The Snowdon Mountain Railway stops running, Hafod Eryri closes its doors, and the mountain rescue teams covering Eryri spend the short days answering calls from people who packed for a walk and got a mountaineering day instead. On the high ground a summer path can turn into a ribbon of ice, and a plateau that took two hours in July can take five with a headwind and knee-deep drifts.

None of that should put you off. A clear winter day above Llyn Idwal, with the Glyderau under snow and nobody else about, is one of the finest things the British hills offer. It just asks for a different approach: check more, carry more, and decide in advance when you will turn around.

Before you leave the house

Most winter epics are decided at the kitchen table, not on the ridge. Give yourself twenty minutes with a brew and go through this properly.

• Mountain weather, not town weather. Read the summit forecast from the Met Office mountain service or MWIS, not the forecast for Betws-y-Coed. What matters is wind speed and gusts, freezing level, cloud base, and when a front is due to arrive.
• Ground conditions. Check recent reports from local outdoor shops, mountain rescue team updates and hill forums. A photograph taken three days ago tells you more about ice and snow cover than any forecast.
• Avalanche risk. Wales has no daily avalanche forecast of the kind Scotland gets, so you have to read the ground yourself: windslab on lee slopes, cornices, recent loading, and the tell-tale whumpf. If you cannot assess a slope, stay off it.
• Daylight. Mid-December in Snowdonia gives you barely eight hours of usable light, and it can be dark by half past four. Plan to be off the tops well before dusk, not racing it down.
• Who you are with. Build the plan around the least experienced person in the group, and agree the route out loud so everyone knows what "Plan B" means.

The winter kit list

Layering does the work here. A wicking base layer, a fleece or two, a synthetic belay jacket and a hardshell will handle almost anything Eryri throws at you, as long as you keep the spare layer dry for when you stop.

On your body

• Winter walking trousers, gaiters, and boots stiff enough to take a crampon with a proper heel and toe welt
• Two pairs of gloves — a thin liner pair you can tie a lace in, plus a warm waterproof pair — and a spare third pair in the pack
• Warm hat, buff, and ski goggles for spindrift on the Carneddau plateau
• A helmet if your route includes anything scrambly, including the easier lines up Crib Goch

In the pack

• Twelve-point crampons, fitted to your boots before you leave the car park, not at the bottom of the slope
• A general mountaineering axe on a leash, and the knowledge to use it for a self-arrest
• Map and compass — the relevant OS Explorer sheet or the Harvey British Mountain Map for Snowdonia — plus a phone as backup, never as primary
• Headtorch with spare batteries, group shelter or bothy bag, and an emergency blanket
• Flask of something hot, food you can eat with gloves on, first aid kit and whistle
• Power bank, and your phone kept in an inside pocket. Cold flattens batteries faster than use does

Skills matter more than shopping

Crampons and an axe are only useful with the skills to go with them. Walking in crampons is a technique in itself: flat-footing on gentle ground, French technique on steeper snow, keeping the points sharp, and never letting a front point catch the back of your other leg. If you have never used them, book a day with a guide or an instructor at a centre such as Plas y Brenin, or go out with someone who genuinely knows what they are doing. Borrowed kit and guesswork is a poor combination above the snowline.

Navigation is the other skill that quietly disappears in winter. Paths vanish under snow, cairns disappear, and features that looked obvious on the map become a white blank. Practise pacing and bearings on a low-level walk in poor weather before you need them at 900 metres. If you can walk a bearing confidently on a featureless hillside, you have bought yourself a lot of margin.

Turn-back points: decide them first

Turn-back points are not a sign of weakness; they are the thing that makes a hard day a good one. Settle them before you start, tell the group, and then hold to them. Consider turning around if:

1. Your hard turnaround time arrives. If you said 13:00 on the summit ridge, that means 13:00, however close the top looks.
2. The wind is knocking you off balance. Once gusts are strong enough that you are staggering or being pushed sideways, the day has changed category.
3. The ground is beyond your kit or your skill. Ice you cannot protect against, deep unconsolidated snow, or a slope you would not want to descend with what is in your pack.
4. You have lost certainty. Ten minutes of not knowing exactly where you are is a warning. Stop, eat, put the map away from the wind and sort it out before you carry on.
5. Someone in the group is cold, quiet, slow or has stopped eating. That is information, not grumbling. Deal with it or turn around.
6. Daylight is shorter than twice the time you need to descend. Descents in the dark are slow, and a slip on ice with a headtorch on is a poor way to finish the day.

If something goes wrong

Dial 999 or 112 and ask for the police, then mountain rescue. Texting 999 works if you have registered for the service in advance, which is worth doing on a quiet evening before your trip. Be ready to give a grid reference, the number in your party, injuries, and a description of what everyone is wearing. Get the casualty off the ground and out of the wind, use the group shelter, and keep them warm.

Cold injuries are time-critical. If someone is shivering uncontrollably, becoming clumsy or vague, treat it as an emergency and get help moving early rather than hoping a descent will fix it on its own. This is general guidance, not medical advice — if you are worried, call and let the professionals decide.

The habit that keeps you safe

Turn around early and often. Most good winter days in Snowdonia end with the summit unvisited and the group still friends, and the ones that do not are usually the days when somebody ignored a feeling at half past twelve. Leave a plan with someone at home, take a photograph of the conditions from the car park, and debrief in the pub with the map open. Next time you will read the hill a little better, and the hill will still be there to read.

Photo: Simon / Pixabay