Safety & disclaimer
OpenFell gives you numbers to plan with. It cannot tell you that a route, a day or a set of conditions is safe — that judgement stays with you, on the ground, with everything you can see and we cannot.
This page is written by Ryan, who has spent eleven years in Scouting, taken several mountaineering courses in the Scottish Highlands in both summer and winter conditions, and led a Ten Tors team across Dartmoor. That is where the emphasis here comes from: winter warnings that are firmer than the summer ones, and a habit of planning around the slowest member of the group. It is not an instructor qualification — nothing below is a substitute for proper training.
"The BMC recognises that climbing, hill walking and mountaineering are activities with a danger of personal injury or death. Participants in these activities should be aware of and accept these risks and be responsible for their own actions and involvement."
British Mountaineering Council
What our numbers are — and are not
Every figure a tool on this site produces is an estimate, computed from a stated formula and from the inputs you typed in. The walking-time calculator applies Naismith's rule with Langmuir and Tranter-style corrections; the daylight planner applies the NOAA solar equations; the weather shown on a peak page is a MET Norway forecast for that summit's coordinates and altitude, and may be up to half an hour old by the time you read it. Each tool tells you which assumptions it used.
None of that amounts to a judgement that a route is within your ability, that a party is equipped for the day, or that conditions will be as forecast. A time estimate does not know about the river in spate, the verglas on the slabs, the member of the group who is quietly struggling, or the visibility on the plateau. Treat the outputs as one input to your planning, alongside a map, a forecast read in full, and an honest assessment of the people you are with.
Conditions change faster than forecasts
A forecast is a probability, issued hours before you read it, for a point on a grid. Hills make their own weather: cloud base drops without warning, wind funnels through bealachs and over cols at multiples of the valley speed, and a summit can be in freezing fog while the car park is in sunshine. Expect the top of the hill to be several degrees colder than the bottom, far windier, and much wetter, and plan for the day you might get rather than the one you were promised.
Winter transforms UK hills
From roughly November to April, and later than that on the higher Scottish hills, a summer walking route becomes a mountaineering route. Snow and ice turn easy ground into a slope you cannot stop yourself on, paths disappear, cornices build over the tops of gullies, and avalanche risk becomes a live consideration. Winter hills demand an ice axe, crampons and — more importantly than either — the training to use them, plus the navigation to cope with a whiteout and the short daylight to fit it all into. If you have not been taught these skills, get taught them before you need them.
Navigation, and the phone that dies
Navigation skill matters more than any app. Phones run out of battery in the cold, lose signal, get dropped, get wet and stop working at exactly the moment the cloud comes down. Carry a paper map and a compass, and know how to take and follow a bearing, pace a leg and relocate when you are not where you thought you were.
Carry, as a minimum, on any UK hill day:
- Map and compass — and the skills to use them
- Headtorch, with spare batteries, on every walk regardless of the finish time you planned
- Spare warm layers and full waterproofs
- More food and drink than you expect to need
- A first-aid kit, an emergency shelter or bothy bag, and a charged phone as a backup, not a plan
Check your planned finish against last light with the daylight safety planner before you set out, and give yourself a margin rather than a deadline.
Call 999 or 112, ask for POLICE, then ask for MOUNTAIN RESCUE. Give your location as precisely as you can — a grid reference if you have one — plus the nature of the injury, the number in the party and your phone battery level.
If your own network has no signal, try 112: an emergency call can connect through any available network. A text may also get through where a call will not, but you must register for emergencySMS in advance by texting register to 999 and following the reply — do it now, at home, not on the hill.
Mountain rescue teams in the UK are volunteers, and calling them out is free. If you are in trouble, call. Do not wait until dark to decide.
Three questions before you go
AdventureSmart puts the whole of pre-trip planning into three questions. If you cannot answer all three with a straight yes, change the plan rather than the answer.
- Do I have the right gear?
- Do I know what the weather will be like?
- Am I confident I have the knowledge and skills for the day?
Whether you are allowed to be somewhere and whether it is safe to be there are two different questions with two different answers. A right of access does not make a crossing passable, and safe ground is not automatically ground you may walk on. Our access rights pages cover the legal side, by jurisdiction, with the date each was last reviewed.
Liability, honestly stated
The information on this site is provided in good faith and drawn from the sources cited on each page and listed in full on the data sources page. We take accuracy seriously, but open datasets contain errors, formulae are approximations, and a page can fall out of date between reviews.
Our estimates are planning aids. They do not constitute advice that any route, activity or set of conditions is safe or suitable for you, and they are not a substitute for appropriate training, current local information and your own judgement. Decisions about whether to set out, where to go, whether to continue and when to turn back are yours, and you remain responsible for them and for the people you take with you.
Where we are wrong, we would rather know. Report an error and we will correct it — see the contact section.
Nothing on this site excludes or restricts any liability that cannot lawfully be excluded or restricted.