P'tites Routes du Soleil: which way and when to ride
The best month for P'tites Routes du Soleil is September: 75% of days were dry with highs of 10–30 °C. In September the wind barely favours either direction — on average 1.6 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 | 9% | 28% | 120 | 5 °C | 0% | 90% | 9.1 † |
| February | 24% | 26% | 91 | 7 °C | 0% | 73% | 10.3 † |
| March | 46% | 31% | 114 | 11 °C | 0% | 44% | 11.8 |
| April | 58% | 34% | 102 | 15 °C | 0% | 17% | 13.5 |
| May | 56% | 43% | 155 | 18 °C | 0% | 5% | 14.9 |
| June | 58% | 38% | 119 | 22 °C | 4% | 0% | 15.7 |
| July | 62% | 30% | 110 | 25 °C | 10% | 0% | 15.3 |
| August | 64% | 25% | 101 | 24 °C | 11% | 0% | 14.1 |
| September | 75% | 25% | 104 | 20 °C | 0% | 1% | 12.5 |
| October | 71% | 23% | 108 | 16 °C | 0% | 10% | 10.8 † |
| November | 36% | 29% | 134 | 9 °C | 0% | 55% | 9.4 † |
| December | 11% | 31% | 143 | 6 °C | 0% | 86% | 8.7 † |
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 Thonon-les-Bains → near Veynes, km/h | Headwind > 15 km/h, Thonon-les-Bains → near Veynes | Headwind > 15 km/h, near Veynes → Thonon-les-Bains | Better way |
|---|---|---|---|---|
| January | +1.2 | 0% | 2% | either |
| February | +1.2 | 1% | 3% | either |
| March | +1.4 | 1% | 4% | either |
| April | +1.5 | 1% | 4% | either |
| May | +1.5 | 1% | 4% | either |
| June | +1.3 | 1% | 3% | either |
| July | +1.7 | 1% | 3% | either |
| August | +1.6 | 0% | 3% | either |
| September | +1.6 | 0% | 3% | either |
| October | +0.7 | 1% | 2% | either |
| November | +0.6 | 1% | 2% | either |
| December | +0.6 | 0% | 1% | either |
Stages
The route is split into 4 stages of about 100–150 km between towns; each stage has its own page.
| Stage | km | Best month | Tailwind Thonon-les-Bains → near Veynes in September, km/h |
|---|---|---|---|
| 1. Thonon-les-Bains → Rumilly | 138 | September | +0.7 |
| 2. Rumilly → Saint-Christophe-sur-Guiers | 119 | September | +1.2 |
| 3. Saint-Christophe-sur-Guiers → Villard-de-Lans | 96 | September | +1.3 |
| 4. Villard-de-Lans → near Veynes | 120 | September | +3.3 |
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.