Your route forecast
Conditions on the route, over the cols & ahead
Hazards & advisories
Measured on the ground
High point, hour by hour
Temperature is lapse-rate corrected to the true altitude. "Feels" is wind chill using the free-air wind at that height, not the sheltered-valley 10 m wind. ⚡ marks thunderstorm hours.
Snow & avalanche
Rain, rockfall & landslide risk
Getting there
Best days to walk
Each day is scored on its own windows: cols/high point 07:00–14:00, trail 07:00–18:00, views 06:00–10:00. Official warnings cap the hours they cover; reported closures cap the next 3 days; later days show the weather outlook.
Do the models agree?
Conditions for your dates
Uses the typical itinerary (7 days). Stages beyond the 7-day forecast show as "not yet forecast" — check back as your date approaches.
Route & freezing level
Where the risk is
Overnight altitudes
Warnings & avalanche bulletins
Latest news & closures
Social & official channels
X, Facebook and Instagram offer no public feed we can read reliably, so these are linked rather than scraped. Treat group posts as unverified until confirmed by Météo-France, the préfecture, the park or the news sources above.
GR5 — Lake Geneva to Chamonix
The first week of the Grande Traversée des Alpes: from Saint-Gingolph on Lake Geneva through the Chablais pastures (Chalets de Bise, Trébentaz, Chésery on the Swiss border), the Golèse and the Giffre valley at Salvagny, over the Col d'Anterne to Moëde-Anterne, and across the Col du Brévent facing Mont Blanc down to Les Houches. Weather risk is thunderstorms on the open cols, snow lingering on the Anterne side early in summer, and rockfall on the Brévent descent.
Help on the trail
Bookings & rules
No permit is needed to walk these routes. Rules for bivouac, dogs and fires differ between parks and change — confirm with the park or refuge before you go.
How the score works
A route is not a point. We pull an hourly forecast for every waypoint (10 on this route), corrected to its real altitude — MET Norway's Locationforecast (ECMWF-based) — plus the past days of rain kept from earlier forecasts and corrected with Météo-France rain gauges. Gusts at the high point, storm energy and the 0 °C level come from Open-Meteo when available; otherwise gusts are estimated from wind speed.
High point — wind at col height (free-air wind at that altitude), wind chill, snowfall, cloud and thunderstorms during the 07:00–14:00 crossing window. Gust bands follow the Beaufort scale (gale force, 62 km/h, impedes walking).
Snow & avalanche — fresh-snow load, new snow depth and time since snowfall give a path status. Where Météo-France (BRA, November–June) or the Swiss SLF publishes an avalanche bulletin, the official danger level is used; otherwise the level shown is a model estimate and is labelled as such.
Rain & slopes — rolling 3–96 h rainfall at each steep section against the European landslide rainfall thresholds of Guzzetti et al. (2007), corrected with Météo-France rain gauges and boosted by rain/flood warnings; the hazard fades once rain stops.
Official warnings — Météo-France Vigilance (and Meteoalarm for the Italian and Swiss stages): orange and red cap the score for the hours they cover; Vigicrues flood vigilance on nearby rivers too.
Reports — French regional press and Google News are classified by relevance, severity and source trust. A credible closure caps the score; a later reopening clears it. Community posts never move the score.
Not an official forecast. Always follow Météo-France warnings and avalanche bulletins, préfecture and park notices, refuge guardians and mountain rescue advice. In an emergency call 112.
Weather forecast from MET Norway (CC BY 4.0). Data: Open-Meteo (gusts & model comparison), Météo-France Vigilance & avalanche bulletins, SLF, Meteoalarm, Hub'eau, Vigicrues, French regional news. All France routes · CoastMetric UK