P'tites Routes du Soleil, stage 2: Rumilly → Saint-Christophe-sur-Guiers
On stage 2 (Rumilly → Saint-Christophe-sur-Guiers, 119 km) the best month is September: 76% of days were dry with highs of 10–30 °C; the wind barely favours either direction (1.2 km/h on average; ERA5 2006–2025, 9:00–18:00).
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Weather by month
| Month | Good days | Rain days ≥ 1 mm | Rain, mm | Avg high | Days ≥ 30 °C | Days < 10 °C | Daylight, h |
|---|---|---|---|---|---|---|---|
| January | 11% | 30% | 132 | 6 °C | 0% | 87% | 9.1 † |
| February | 30% | 26% | 96 | 8 °C | 0% | 65% | 10.3 † |
| March | 53% | 31% | 120 | 12 °C | 0% | 34% | 11.8 |
| April | 64% | 32% | 101 | 16 °C | 0% | 10% | 13.5 |
| May | 58% | 41% | 159 | 19 °C | 0% | 2% | 14.9 |
| June | 58% | 36% | 119 | 23 °C | 7% | 0% | 15.7 |
| July | 57% | 28% | 113 | 26 °C | 18% | 0% | 15.4 |
| August | 59% | 24% | 102 | 25 °C | 18% | 0% | 14.1 |
| September | 76% | 24% | 108 | 21 °C | 0% | 1% | 12.5 |
| October | 74% | 22% | 109 | 16 °C | 0% | 8% | 10.8 † |
| November | 38% | 30% | 137 | 10 °C | 0% | 51% | 9.4 † |
| December | 13% | 33% | 156 | 6 °C | 0% | 83% | 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 Rumilly → Saint-Christophe-sur-Guiers, km/h | Headwind > 15 km/h, Rumilly → Saint-Christophe-sur-Guiers | Headwind > 15 km/h, Saint-Christophe-sur-Guiers → Rumilly | Better way |
|---|---|---|---|---|
| January | +0.8 | 0% | 0% | either |
| February | +0.8 | 0% | 0% | either |
| March | +0.9 | 0% | 1% | either |
| April | +1.2 | 0% | 1% | either |
| May | +1.2 | 0% | 1% | either |
| June | +1.1 | 0% | 0% | either |
| July | +1.3 | 0% | 0% | either |
| August | +1.3 | 0% | 0% | either |
| September | +1.2 | 0% | 0% | either |
| October | +0.8 | 0% | 0% | either |
| November | +0.6 | 0% | 0% | either |
| December | +0.5 | 0% | 0% | either |
Along the route (sections of about 25 km)
| km | Heading | Tailwind in September, km/h |
|---|---|---|
| 138–163 | SW | +0.6 |
| 163–188 | S | +1.0 |
| 188–214 | SW | −0.6 |
| 214–239 | SE | +3.0 |
| 239–257 | S | +2.5 |
Other stages
- Thonon-les-Bains → Rumilly 138 km
- Rumilly → Saint-Christophe-sur-Guiers 119 km
- Saint-Christophe-sur-Guiers → Villard-de-Lans 96 km
- Villard-de-Lans → near Veynes 120 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.