safety
Reading Mountain Weather: MWIS, Met Office & Yr.no Compared
MWIS, Met Office and Yr.no compared — which to trust for which question, and the one number that matters more than temperature.
Quick Summary
- MWIS (Mountain Weather Information Service) is the only forecast written specifically for hillwalkers — it tells you what conditions feel like on the summit, not what the weather is doing in the valley
- Wind speed matters more than temperature — a 5°C summit with 40mph wind has an effective temperature of -10°C, and that is what kills people
- Use three sources together: MWIS for mountain-specific narrative, Met Office for hourly detail, Yr.no for multi-day trends
- Check before every walk — our Daylight Hours Planner shows sunrise and sunset alongside your weather planning so you know how many hours you actually have
I check three weather forecasts before every Scottish hill day. Not because I am obsessive, but because each one tells me something the others do not. The Met Office tells me when it will rain. MWIS tells me what it feels like on the summit. Yr.no tells me whether Thursday is worth taking as a day off work. None of them is complete on its own. Together, they give you enough information to make a good decision about whether to go, what to wear, and when to turn back.
Most walkers check one forecast — usually the BBC or their phone's default app — glance at the temperature and the rain icon, and set off. This is how people end up hypothermic on a 12°C day because the valley temperature told them nothing about the 60mph wind on the ridge.
Quick Answer: For Scottish hillwalking, use MWIS (mwis.org.uk) as your primary mountain forecast — it covers six Scottish areas with summit-specific wind, temperature, cloud base, visibility and freezing level written by meteorologists who climb. Supplement with Met Office Mountain Forecast for hourly breakdown, and Yr.no for 7-10 day planning. The critical number is wind speed at summit altitude, not valley temperature. A wind speed above 40mph makes most ridge walks inadvisable; above 60mph, stay off the hill.
MWIS — the mountain forecast
The Mountain Weather Information Service is funded by mountaineering organisations and written by meteorologists who are also climbers. It covers six Scottish mountain areas: West Highlands, East Highlands, Monadhliath & Cairngorms, Southern Uplands, NW Highlands, and Skye & the islands.
What it gives you that others don't:
- Freezing level — the altitude above which surfaces are icy. If the freezing level is 700m and your summit is 1,000m, you need crampons.
- Cloud base — the altitude at which you enter cloud. If the cloud base is 600m and your Munro is 1,000m, you will navigate the top 400m in zero visibility.
- Wind speed at summit level — not at sea level, not at the weather station, but at the height you will actually be walking.
- Subjective assessment — MWIS forecasters write a narrative: "A raw day on the tops with hill fog persisting" tells you more than an icon.
When to use it: Before every hill day. Read it the evening before and again in the morning. MWIS updates at 16:00 daily.
Met Office Mountain Forecast
The Met Office publishes mountain area forecasts and, more usefully, hourly spot forecasts for specific locations. The Met Office app and website let you search for a hill by name and get an hour-by-hour breakdown of temperature, wind, rain probability and visibility at different altitudes.
What it gives you that others don't:
- Hourly resolution — rain at 09:00 clearing by 12:00 means a later start, not a cancelled day
- Rain probability — a 40% chance of rain is very different from 90%
- Spot forecasts — search "Ben Nevis summit" and get a forecast for 1,345m, not Fort William town
When to use it: For timing decisions. MWIS tells you the character of the day; Met Office tells you which hours are best.
Try it yourself
Our free Daylight Hours Planner
shows exact sunrise, sunset and civil twilight for your walking location on your date — essential context alongside your weather forecast for timing your start.
No sign-up required.Yr.no — the Norwegian option
Yr.no (from the Norwegian Meteorological Institute) is not a UK service, but its 7-10 day forecasts for Scottish locations are consistently good — often better than the Met Office for multi-day trends. The interface is clean, the data is detailed, and it is free.
What it gives you that others don't:
- 7-10 day outlook — useful for planning which day of the week to walk
- Wind direction — critical for choosing which side of a hill to approach
- Honest uncertainty — Yr.no shows confidence intervals on longer-range forecasts rather than pretending Thursday's weather is known precisely
When to use it: Monday evening, deciding which day this week is best for the hill. Not for day-of decisions — MWIS and Met Office are better for that.
The numbers that matter
Forget the temperature icon on your phone. These are the numbers that determine whether your day is safe and enjoyable:
Wind speed at summit altitude
This is the single most important number. Wind determines:
- Whether you can stand on a ridge
- Your effective temperature (wind chill)
- Whether cloud and rain feel survivable or desperate
| Wind speed (summit) | Conditions | Decision |
|---|---|---|
| 0-20mph | Comfortable | Go — all routes |
| 20-35mph | Breezy, affects balance on exposed ridges | Go — avoid narrow ridges |
| 35-50mph | Difficult to walk, painful on exposed ground | Sheltered routes only |
| 50-70mph | Dangerous on any exposed ground | Low-level walks or stay home |
| 70mph+ | Survival conditions | Stay off the hill |
Freezing level
If the freezing level is below your summit height, surfaces above that level may be icy. Below 800m in winter means crampons and ice axe for any Munro. Below 500m means even Corbetts and Grahams need winter kit.
Cloud base
If the cloud base is below your summit, you will be navigating in cloud. On a well-pathed Munro like Ben Lomond this is manageable. On a featureless plateau like the Cairngorms, it demands confident compass work.
How I use them together
My actual process before a hill day:
Sunday evening: Check Yr.no for the week ahead. Pick the best day. Check MWIS 4-day outlook for that day.
Night before: Read MWIS in full — narrative, wind table, freezing level, cloud base. Check Met Office hourly for the specific hill. Decide: go, change route, or cancel.
Morning of: Re-check MWIS morning update (if available) and Met Office hourly. Look out the window. Make final decision.
On the hill: Reassess constantly. If conditions are worse than forecast — higher wind, lower cloud, colder than expected — shorten the route or turn back. The forecast is a prediction, not a guarantee.
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Try it yourself
Our free Naismith's Rule Calculator
estimates walking time with weather multipliers — headwinds and poor visibility slow you down. Factor weather into timing, not just distance and ascent.
No sign-up required.Frequently Asked Questions
Which is the most accurate mountain weather forecast for Scotland?
MWIS is the most mountain-specific and consistently reliable for summit conditions. Met Office is best for hourly timing and rain probability. Yr.no is best for multi-day planning. No single source is most accurate for everything — use all three together.
Is the BBC weather forecast good enough for hillwalking?
No. The BBC forecast is a valley forecast. It tells you the temperature and rain chance for the nearest town, not for the summit. A BBC forecast of "12°C, light rain" might correspond to "2°C, 50mph wind, zero visibility, horizontal sleet" at 1,000m. Always use MWIS or Met Office mountain forecasts for hill days.
What wind speed is too high for hillwalking?
As a general guide: above 40mph at summit level, avoid exposed ridges. Above 50mph, only sheltered glen walks are advisable. Above 60mph, experienced mountaineers turn back. These are summit wind speeds from MWIS, not valley winds from your phone app.
How far ahead can I trust a Scottish mountain forecast?
Reliably: 24-36 hours. Roughly: 3-4 days. Beyond 5 days, Scottish weather forecasts are trend indicators, not predictions. Always re-check the morning of your walk.
What is wind chill and why does it matter?
Wind chill is the effective temperature your body experiences when wind removes heat from exposed skin. At 5°C with 40mph wind, the wind chill is approximately -10°C. At 0°C with 60mph wind, it is below -20°C. Wind chill causes frostbite and hypothermia far faster than the air temperature alone would suggest. This is why summit wind speed matters more than valley temperature.
Related Articles
- Winter Hillwalking in Scotland: Essential Skills — when weather interpretation becomes life-critical
- Scotland Month-by-Month: When to Walk, What to Expect — seasonal weather patterns
- What to Wear Hillwalking in Scotland — the layering system that handles weather changes
- Daylight Hours Planner — sunrise, sunset and usable hours for any date
- Naismith's Rule Calculator — weather-adjusted walking times
This article is for informational purposes only and does not constitute professional instruction or safety guidance. Weather forecasts are predictions, not guarantees — conditions on Scottish mountains can change rapidly and without warning. Always carry appropriate equipment for the worst plausible conditions, not the forecast conditions. Turn back if conditions deteriorate beyond your comfort level. OutdoorSCOT is not liable for any incidents arising from the use of this information.
Sources
- Mountain Weather Information Service — MWIS
- Met Office — Mountain Forecasts — Met Office
- Yr.no — Norwegian Meteorological Institute — MET Norway
- Mountaineering Scotland — Weather — Mountaineering Scotland
- Scottish Avalanche Information Service — SAIS