La Voie Bleue, stage 4: Port-sur-Saône → Auxonne
On stage 4 (Port-sur-Saône → Auxonne, 119 km) the best month is September: 75% of days were dry with highs of 10–30 °C; the wind barely favours either direction (0.5 km/h on average; ERA5 2006–2025, 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 | 11% | 27% | 91 | 6 °C | 0% | 81% | 8.8 † |
| February | 27% | 26% | 72 | 8 °C | 0% | 64% | 10.2 † |
| March | 56% | 26% | 76 | 12 °C | 0% | 30% | 11.8 |
| April | 70% | 25% | 71 | 17 °C | 0% | 9% | 13.6 |
| May | 67% | 31% | 97 | 20 °C | 2% | 1% | 15.1 |
| June | 61% | 27% | 84 | 25 °C | 13% | 0% | 15.9 |
| July | 54% | 24% | 65 | 27 °C | 26% | 0% | 15.6 |
| August | 58% | 20% | 73 | 26 °C | 23% | 0% | 14.2 |
| September | 75% | 20% | 74 | 22 °C | 5% | 0% | 12.5 |
| October | 75% | 22% | 90 | 17 °C | 0% | 5% | 10.8 † |
| November | 38% | 27% | 95 | 10 °C | 0% | 47% | 9.2 † |
| December | 12% | 31% | 106 | 7 °C | 0% | 77% | 8.5 † |
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 Port-sur-Saône → Auxonne, km/h | Headwind > 15 km/h, Port-sur-Saône → Auxonne | Headwind > 15 km/h, Auxonne → Port-sur-Saône | Better way |
|---|---|---|---|---|
| January | −3.9 | 21% | 5% | Auxonne → Port-sur-Saône |
| February | −3.0 | 19% | 8% | Auxonne → Port-sur-Saône |
| March | −1.6 | 17% | 9% | either |
| April | +0.5 | 9% | 9% | either |
| May | −0.3 | 9% | 9% | either |
| June | +0.1 | 6% | 6% | either |
| July | −1.1 | 7% | 3% | either |
| August | −1.7 | 7% | 2% | either |
| September | −0.5 | 9% | 7% | either |
| October | −2.4 | 14% | 4% | Auxonne → Port-sur-Saône |
| November | −4.0 | 18% | 4% | Auxonne → Port-sur-Saône |
| December | −5.0 | 21% | 4% | Auxonne → Port-sur-Saône |
Along the route (sections of about 25 km)
| km | Heading | Tailwind in September, km/h |
|---|---|---|
| 345–370 | SW | −0.9 |
| 370–396 | SW | −0.8 |
| 396–421 | SW | −0.6 |
| 421–447 | S | −0.1 |
| 447–463 | S | −0.1 |
Other stages
- Hagondange → Metz 90 km
- Metz → Épinal 139 km
- Épinal → Port-sur-Saône 106 km
- Port-sur-Saône → Auxonne 119 km
- Auxonne → Chalon-sur-Saône 99 km
- Chalon-sur-Saône → Lyon 148 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.