Pick the right hill for the weather — and your appetite.
Hillfinder ranks hills and mountains by how good the forecast is on the summit - not in the glen below - so you can spend a good-weather window on the right one instead of guessing.
Each summit's grid-point forecast is corrected up to its real height, scored for the kind of day you want, and checked against hard safety gates. It starts with Scotland's Munros and Corbetts, with more regions and hill lists to come.
How the ranking works
Weather models smooth the terrain flat. Each hourly forecast is lifted from the grid elevation up to the hill's true summit - colder, windier, and more often in cloud than the raw figure below.
Four factors - wind, precipitation, a cloud-free summit and visibility - are combined into a 0–10 score across the 08:00–18:00 window, weighted by the profile and season you choose.
Before ranking, dangerous conditions are removed outright - not just marked down - with the reason and the hill's own forecast value shown, so an exclusion is always understood.
Choose what a good day means
The same four factors, split three ways. Each bar shows the summer weighting as one whole - the wider a factor's slice, the more it counts towards the score. Switch profiles anytime; the ranking re-sorts instantly.
A sensible default with no single axis dominating - wind, rain and a clear summit carry near-equal weight.
Minimise the chance of a bad day out. Wind dominates, since it's the condition that most often turns a walk dangerous.
Maximise the chance of actually seeing something from the top. A cloud-free summit and long visibility lead.
What the score is made of
The numbers behind a score are always shown, never hidden behind a verdict - here's what each one means and how far to trust it.
Wind speed is extrapolated to the true summit height from the model's own 10 m and 80 m levels, following a logarithmic profile - physically grounded, not a flat guess. Gusts are weaker: no reading exists above 10 m, so they're scaled by a crude multiplier not yet calibrated against station data. Treat the absolute gust with some caution, though it still tracks windier vs. calmer days.
How much the top sits in cloud, from a standard approximation (a rising parcel's condensation height) driven by forecast humidity, with a gradual band around the estimated cloud base. It tells genuine hill fog apart from a high sky that never touches the summit - but it's a theoretical estimate, not observed cloud, and can be too pessimistic on humid, still nights.
Forecast rain probability and amount combined - a low-chance downpour and an all-day drizzle are treated differently, not just averaged into one number.
Forecast horizontal visibility: a clear day for looking across to the next ridge, or a murky one where you can barely see the cairn. Weighted most in Views, moderately in Balanced.
The wind-chill-corrected summit temperature, so a cold top in a strong wind reads as the harsher day it is. It isn't scored in summer (almost every day scored near-perfect, so it moved no ranking); instead it drives a hard gate at the dangerous extremes.
The modelled altitude where the air hits 0°C, from a fixed lapse rate. A reasonable average, but it can be badly wrong under a winter anticyclone, where the summit can be warmer than the glen.
Reading the map
Each hill is a triangle coloured by its score for the day and profile you've picked - so a good-weather window is the same colour wherever it is on the map.
A shortlist worth driving to.
Alongside the map, Top Picks pulls out the five best hills for the day at a glance - so you don't have to scan hundreds of markers to find the good ones.
Neighbouring hills share almost identical weather, so one good-weather corner could sweep all five slots. Top Picks caps it at one hill per region - five genuinely different days out, spread across the country.
Change the profile, day or gates and the shortlist re-sorts instantly - always the best five for exactly what you've asked for. Tap one to find it on the map.
Why some hills disappear
A hard gate is an exclusion, not a low score: a day that fails one is removed from the ranking entirely, so a genuinely dangerous day can't be outweighed by a good score elsewhere. Four gates are active - all adjustable in Settings, where you can raise a limit, widen a range, or turn a gate off.
Summer now, winter next
Profiles are seasonal. Summer is wired today. Winter is coming and will add its own gating - avalanche hazard, a daylight-margin check and a cold-comfort weighting - rather than just widening the summer gates. Until then, selecting winter falls back to the summer profiles so nothing breaks.
What it can't do yet
- Gusts are approximate. They rely on a crude multiplier not yet calibrated against real weather stations. Summit wind speed is better founded; gusts have no upper level to work from.
- Cloud is modelled, not observed. The cloud-base estimate can over-call cloud on humid, calm nights and miss an elevated deck on a temperature inversion.
- The freezing level uses a fixed lapse rate. It can invert under a winter anticyclone - summit warmer than the valley on exactly the days that matter most.
- The walk-in isn't modelled. Summit conditions are shown, not the approach, and the spread of Top Picks across the country is a coarse proxy for a real route.
Where the data comes from
Hillfinder doesn't generate weather or survey hills - it combines a few open sources and does the summit-correction and scoring on top.
Summits, heights and classifications come from the Database of British and Irish Hills (DoBIH) - the definitive community-maintained list behind Munros, Corbetts and the rest.
Hourly forecasts come from Open-Meteo, a free weather API. Each hill's grid-point values are then corrected up to its true summit height before scoring.
Base maps are built from OpenStreetMap data, styled with CARTO basemaps and a terrain layer for the main view.
The summit correction, the four-factor score and the safety gates are all Hillfinder's own, deterministic and explainable - no black-box model deciding what you see.
This is a forecasting tool: it informs a decision, it doesn't make one, and it can't stop anyone heading out in bad conditions. The gates and profiles shape which hills a ranking shows you, not whether a hill is safe to climb - so weigh the numbers with your own judgement, especially for wind.