La Belle Via (Villard-Bonnot – Chateauneuf-sur-Isère (ViaRhôna))): which way and when to ride
The best month for La Belle Via (Villard-Bonnot – Chateauneuf-sur-Isère (ViaRhôna))) is September: 74% of days were dry with highs of 10–30 °C. In September the wind barely favours either direction — on average 0.2 km/h along the route (ERA5 2006–2025, daytime 9:00–18:00).
Weather by month
| Month | Good days | Rain days ≥ 1 mm | Rain, mm | Avg high | Days ≥ 30 °C | Days < 10 °C | Daylight, h |
|---|---|---|---|---|---|---|---|
| January | 10% | 28% | 116 | 5 °C | 0% | 87% | 9.1 † |
| February | 26% | 25% | 88 | 7 °C | 0% | 70% | 10.3 † |
| March | 46% | 30% | 110 | 11 °C | 0% | 44% | 11.8 |
| April | 59% | 33% | 100 | 15 °C | 0% | 19% | 13.4 |
| May | 57% | 42% | 157 | 18 °C | 0% | 7% | 14.9 |
| June | 58% | 36% | 116 | 22 °C | 6% | 0% | 15.6 |
| July | 60% | 26% | 102 | 25 °C | 15% | 0% | 15.3 |
| August | 63% | 24% | 94 | 24 °C | 15% | 0% | 14.1 |
| September | 74% | 25% | 102 | 20 °C | 1% | 2% | 12.5 |
| October | 72% | 22% | 103 | 16 °C | 0% | 11% | 10.8 † |
| November | 36% | 30% | 134 | 9 °C | 0% | 54% | 9.4 † |
| December | 13% | 31% | 138 | 6 °C | 0% | 83% | 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 Villard-Bonnot → Chateauneuf-sur-Isère (ViaRhôna)), km/h | Headwind > 15 km/h, Villard-Bonnot → Chateauneuf-sur-Isère (ViaRhôna)) | Headwind > 15 km/h, Chateauneuf-sur-Isère (ViaRhôna)) → Villard-Bonnot | Better way |
|---|---|---|---|---|
| January | +0.9 | 0% | 0% | either |
| February | +0.5 | 1% | 0% | either |
| March | +0.1 | 1% | 1% | either |
| April | 0.0 | 1% | 1% | either |
| May | 0.0 | 1% | 1% | either |
| June | −0.1 | 1% | 0% | either |
| July | +0.3 | 1% | 0% | either |
| August | +0.2 | 1% | 0% | either |
| September | +0.2 | 1% | 0% | either |
| October | 0.0 | 1% | 0% | either |
| November | +0.5 | 0% | 0% | either |
| December | +0.7 | 0% | 0% | either |
Along the route (sections of about 25 km)
| km | Heading | Tailwind in September, km/h |
|---|---|---|
| 0–6 | NE | −0.7 |
| 6–31 | NE | −1.0 |
| 31–38 | NE | −0.8 |
| 38–63 | S | +1.8 |
| 63–89 | S | +2.4 |
| 89–115 | SW | +0.7 |
| 115–141 | W | −2.9 |
| 141–166 | W | −0.6 |
| 166–191 | SW | +1.1 |
| 191–216 | W | −0.7 |
| 216–239 | SW | +1.5 |
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.