La Véloscénie, stage 4: Chartres → Antony
On stage 4 (Chartres → Antony, 112 km) the best month is September: 81% of days were dry with highs of 10–30 °C; the wind barely favours either direction (1.9 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 | 16% | 21% | 56 | 7 °C | 0% | 76% | 8.7 † |
| February | 29% | 22% | 49 | 8 °C | 0% | 61% | 10.1 † |
| March | 51% | 26% | 56 | 12 °C | 0% | 33% | 11.7 |
| April | 72% | 24% | 46 | 16 °C | 0% | 7% | 13.6 |
| May | 71% | 29% | 69 | 19 °C | 0% | 1% | 15.2 |
| June | 70% | 25% | 65 | 22 °C | 6% | 0% | 16.1 |
| July | 72% | 18% | 51 | 25 °C | 12% | 0% | 15.8 |
| August | 73% | 18% | 53 | 24 °C | 10% | 0% | 14.3 |
| September | 81% | 16% | 46 | 21 °C | 3% | 0% | 12.5 |
| October | 75% | 22% | 69 | 16 °C | 0% | 3% | 10.7 † |
| November | 47% | 22% | 60 | 11 °C | 0% | 38% | 9.1 † |
| December | 21% | 22% | 66 | 8 °C | 0% | 68% | 8.3 † |
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 Chartres → Antony, km/h | Headwind > 15 km/h, Chartres → Antony | Headwind > 15 km/h, Antony → Chartres | Better way |
|---|---|---|---|---|
| January | +5.7 | 4% | 24% | Chartres → Antony |
| February | +4.4 | 7% | 23% | Chartres → Antony |
| March | +2.3 | 8% | 19% | Chartres → Antony |
| April | 0.0 | 9% | 11% | either |
| May | +1.4 | 7% | 14% | either |
| June | +1.5 | 6% | 12% | either |
| July | +4.4 | 3% | 17% | Chartres → Antony |
| August | +4.5 | 2% | 15% | Chartres → Antony |
| September | +1.9 | 6% | 13% | either |
| October | +3.3 | 4% | 17% | Chartres → Antony |
| November | +5.2 | 3% | 22% | Chartres → Antony |
| December | +6.4 | 4% | 25% | Chartres → Antony |
Along the route (sections of about 25 km)
| km | Heading | Tailwind in September, km/h |
|---|---|---|
| 342–367 | N | +1.0 |
| 367–393 | E | +2.5 |
| 393–418 | E | +2.3 |
| 418–443 | NE | +1.8 |
| 443–454 | SE | +2.1 |
Other stages
- near Pontorson → Domfront 98 km
- Domfront → Mortagne-au-Perche 113 km
- Mortagne-au-Perche → Chartres 114 km
- Chartres → Antony 112 km
- Antony → Paris 72 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.