Grands Montets
📍 Rhone-Alpes , Departement de la Haute-Savoie · Nearest city: Chamonix-Mont-Blanc (8 km)
58 XC score / 100 · takeoff at 3234 m · 📍 View on map
Coordinates and external links
45.94780, 6.96000Forecast next days
Updated: 2026-04-20 12:35 UTC · Source: Open-Meteo · Thermal window 10:00–18:00 local time
Día volable, condiciones decentes, base de cúmulos ~1275 m, viento 21 km/h.
base ~1275m · wind 21 km/hDía volable, condiciones decentes, base de cúmulos ~977 m, viento 21 km/h.
base ~977m · wind 21 km/hDía volable, condiciones decentes, base de cúmulos ~1105 m, viento 7 km/h.
base ~1105m · wind 7 km/hDía volable, condiciones decentes, base de cúmulos ~1593 m, viento 9 km/h.
base ~1593m · wind 9 km/hComposite flyability score (CAPE + LI + wind + precip + low clouds). Cross-check with local pilots before flying.
Detailed hourly weather
2026-04-20⚠️ Marginal · peak 50 at 9h
- Cloud suck alto (98/100) — base bajo freezing con CU
| 08 30 ☁️⚠️ | 09 50 ☁️⚠️ | 10 50 ☁️⚠️ | 11 50 ☁️⚠️ | 12 50 ☁️⚠️ 🏔️ | 13 40 ☁️⚠️ 🏔️ | 14 40 ☁️⚠️ 🏔️ | 15 40 ☁️⚠️ 🏔️ | 16 45 ☁️⚠️ 🏔️ | 17 40 ☁️⚠️ 🏔️ | 18 48 ☁️⚠️ 🏔️ | 19 30 ☁️⚠️ 🏔️ | 20 40 ☁️⚠️ 🏔️ |
Peak 9h: CAPE 0 J/kg · LI 3.3 · BL top 210 m · w* 0.0 m/s · cloud base 6359 m · 0°C at 3250 m · Pro score 64/100 · sun 30° over slope
2026-04-21⚠️ Marginal · peak 55 at 16h
- Cloud suck alto (88/100) — base bajo freezing con CU
| 08 30 ☁️⚠️ | 09 30 ☁️⚠️ | 10 30 ☁️⚠️ | 11 50 ☁️⚠️ | 12 50 ☁️⚠️ | 13 50 ☁️⚠️ | 14 50 ☁️⚠️ | 15 50 ☁️⚠️ | 16 55 ☁️⚠️ | 17 55 ☁️⚠️ | 18 50 ☁️⚠️ | 19 50 ☁️⚠️ | 20 35 ☁️⚠️ |
Peak 16h: CAPE 0 J/kg · LI 1.9 · BL top 1470 m · w* 0.0 m/s · cloud base 4271 m · 0°C at 2580 m · Pro score 66/100 · sun 24° over slope
Hourly flyability (0–100). ⛈️ = storm risk · ☁️⚠️ = cloud suck · 🏔️ = active ridge lift. CAPE = convective energy, LI = stability, BL top = thermal ceiling, w* = estimated dry thermal velocity. Source: Open-Meteo (ECMWF/GFS/ICON blend model).
Estimated vertical profile (Sounding)
Reference time: 09:00 (peak of the day)
Surface T: -5.4°C · Td: -30.4°C
LCL (cloud base): 3125 m
BL top: 210 m
0°C level: 3250 m
Approximate profile from surface variables + synoptic levels. Red lines = temperature, dashed blue = dew point. Orange bands = detected inversions.
Takeoff orientations
Green = good orientation · Yellow = possible · Gray = not suitable
Why this site has thermal potential
| Factor | Value | Interpretation |
|---|---|---|
| Hotspot density (5 km) | 6 | Medium |
| Avg thermal probability | 0.82 | Based on thousands of aggregated IGC flights |
| Solar orientation | 0.35 | Slope faces south in northern hemisphere |
| Own flight history | 0.00 | Thermals detected in platform IGC tracks |
Takeoff description
high altitude take off (3250m), which can be reached with a cable car. The take off is on a glacier be carefull with the crevasses.... it's better to go there with a mountain guide. JULY/ AUGUST: actual TO lies OUTSIDE no-fly zone, but route of flight has to be selected carefully ( > see pix!)
Rules and notes
>> July-August: be aware of no-fly-zone on south side of Chamonix (Mont Blanc -Aiguille du Midi)! (> see pix) >> LF R-30A active year round!! (> see pix!)
Pilot comments
one of the nicest flight of Chamonix
Nearby sites
Flegere (65) · Plan Praz/ Brevent (Chamonix) (56) · Plan de l'Aiguille (Chamonix) (50) · Aiguille du Midi -S / N (61) · Loriaz (55) · Tete noire de Pormenaz (48)