RAVeL W5 D'une vallée à l'autre: which way and when to ride
The best month for RAVeL W5 D'une vallée à l'autre is September: 76% of days were dry with highs of 10–30 °C. In September, riding Bouillon → Hoegaarden meant an average tailwind of 2.0 km/h (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 | 4% | 30% | 83 | 5 °C | 0% | 91% | 8.5 † |
| February | 12% | 29% | 71 | 6 °C | 0% | 82% | 10.0 † |
| March | 38% | 29% | 71 | 10 °C | 0% | 53% | 11.7 |
| April | 61% | 27% | 53 | 14 °C | 0% | 23% | 13.7 |
| May | 66% | 32% | 76 | 17 °C | 0% | 4% | 15.4 |
| June | 68% | 31% | 84 | 21 °C | 2% | 0% | 16.4 |
| July | 66% | 29% | 81 | 22 °C | 6% | 0% | 16.0 |
| August | 65% | 31% | 88 | 22 °C | 5% | 0% | 14.5 |
| September | 76% | 23% | 67 | 19 °C | 1% | 0% | 12.5 |
| October | 66% | 25% | 77 | 14 °C | 0% | 12% | 10.6 † |
| November | 26% | 30% | 74 | 9 °C | 0% | 61% | 8.9 † |
| December | 7% | 29% | 89 | 6 °C | 0% | 86% | 8.1 † |
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 Hoegaarden → Bouillon, km/h | Headwind > 15 km/h, Hoegaarden → Bouillon | Headwind > 15 km/h, Bouillon → Hoegaarden | Better way |
|---|---|---|---|---|
| January | −5.3 | 25% | 5% | Bouillon → Hoegaarden |
| February | −4.6 | 24% | 7% | Bouillon → Hoegaarden |
| March | −1.7 | 17% | 8% | either |
| April | +0.3 | 11% | 9% | either |
| May | +0.5 | 10% | 9% | either |
| June | +0.4 | 8% | 7% | either |
| July | −0.9 | 9% | 4% | either |
| August | −2.0 | 10% | 4% | either |
| September | −2.0 | 12% | 5% | Bouillon → Hoegaarden |
| October | −5.1 | 22% | 4% | Bouillon → Hoegaarden |
| November | −6.5 | 26% | 4% | Bouillon → Hoegaarden |
| December | −6.6 | 27% | 4% | Bouillon → Hoegaarden |
Along the route (sections of about 25 km)
| km | Heading | Tailwind in September, km/h |
|---|---|---|
| 0–25 | S | −2.5 |
| 25–50 | S | −2.9 |
| 50–75 | S | −2.4 |
| 75–101 | S | −2.4 |
| 101–127 | E | +1.7 |
| 127–152 | S | −3.3 |
| 152–179 | SW | −3.6 |
| 179–187 | E | +2.0 |
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.