Route des Grandes Alpes à vélo - Tracé principal, stage 3: Modane → Guillestre
On stage 3 (Modane → Guillestre, 134 km) the best month is August: 71% of days were dry with highs of 10–30 °C; the wind barely favours either direction (0.0 km/h on average; ERA5 2006–2025, 9:00–18:00).
← Route des Grandes Alpes à vélo - Tracé principal (Whole route)
Weather by month
| Month | Good days | Rain days ≥ 1 mm | Rain, mm | Avg high | Days ≥ 30 °C | Days < 10 °C | Daylight, h |
|---|---|---|---|---|---|---|---|
| January | 0% | 24% | 98 | -4 °C | 0% | 100% | 9.1 † |
| February | 0% | 23% | 74 | -2 °C | 0% | 100% | 10.3 † |
| March | 1% | 27% | 103 | 1 °C | 0% | 99% | 11.8 |
| April | 10% | 29% | 87 | 5 °C | 0% | 90% | 13.4 |
| May | 26% | 45% | 122 | 9 °C | 0% | 59% | 14.8 |
| June | 48% | 49% | 106 | 15 °C | 0% | 11% | 15.6 |
| July | 64% | 36% | 79 | 18 °C | 0% | 2% | 15.3 |
| August | 71% | 29% | 70 | 18 °C | 0% | 3% | 14.1 |
| September | 63% | 30% | 73 | 14 °C | 0% | 16% | 12.4 |
| October | 43% | 24% | 89 | 9 °C | 0% | 52% | 10.9 † |
| November | 4% | 27% | 123 | 2 °C | 0% | 96% | 9.5 † |
| December | 0% | 26% | 121 | -3 °C | 0% | 100% | 8.8 † |
Best months are all months within 3 percentage points of the best one. † less than 11 hours of daylight — long stages get tight.
Wind by month
| Month | Wind Modane → Guillestre, km/h | Headwind > 15 km/h, Modane → Guillestre | Headwind > 15 km/h, Guillestre → Modane | Better way |
|---|---|---|---|---|
| January | +0.9 | 0% | 0% | either |
| February | +0.6 | 0% | 0% | either |
| March | +0.5 | 0% | 0% | either |
| April | +0.2 | 0% | 0% | either |
| May | +0.1 | 0% | 0% | either |
| June | −0.2 | 0% | 0% | either |
| July | 0.0 | 0% | 0% | either |
| August | 0.0 | 0% | 0% | either |
| September | −0.1 | 0% | 0% | either |
| October | −0.2 | 0% | 0% | either |
| November | +0.3 | 0% | 0% | either |
| December | +0.8 | 0% | 0% | either |
Along the route (sections of about 25 km)
| km | Heading | Tailwind in August, km/h |
|---|---|---|
| 278–303 | W | −3.5 |
| 303–328 | S | +1.1 |
| 328–353 | SE | +2.7 |
| 353–379 | SE | +2.0 |
| 379–404 | S | −1.2 |
| 404–412 | SW | −3.6 |
Other stages
- Thonon-les-Bains → Beaufort 128 km
- Beaufort → Modane 151 km
- Modane → Guillestre 134 km
- Guillestre → Péone 116 km
- Péone → Nice 168 km
How to read the numbers
Wind is the 10 m wind of a 25-km grid cell, daytime hours 9:00–18:00 local solar time; at saddle height in a sheltered valley it is weaker, on a coast or ridge stronger. A positive value is a tailwind. ERA5 slightly over-counts days with ≥ 1 mm of rain (by about 5–7 percentage points) and underestimates daily highs by 1–2 °C. Good day = less than 1 mm of rain between 9:00 and 18:00 (riding hours, local solar time) and a high between 10 and 30 °C; rain at night or in the evening does not spoil it.