Heuvelroute, stage 4: Tienen → Hombourg
On stage 4 (Tienen → Hombourg, 114 km) the best month is September: 77% of days were dry with highs of 10–30 °C, and riding Tienen → Hombourg meant an average tailwind of 3.7 km/h (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 | 6% | 30% | 78 | 5 °C | 0% | 87% | 8.4 † |
| February | 16% | 29% | 65 | 7 °C | 0% | 76% | 9.9 † |
| March | 42% | 27% | 65 | 10 °C | 0% | 48% | 11.7 |
| April | 65% | 24% | 46 | 15 °C | 0% | 19% | 13.7 |
| May | 70% | 29% | 70 | 18 °C | 0% | 3% | 15.5 |
| June | 69% | 28% | 81 | 21 °C | 3% | 0% | 16.5 |
| July | 64% | 30% | 82 | 23 °C | 8% | 0% | 16.1 |
| August | 64% | 30% | 85 | 22 °C | 7% | 0% | 14.5 |
| September | 77% | 21% | 62 | 19 °C | 1% | 0% | 12.5 |
| October | 69% | 24% | 72 | 15 °C | 0% | 10% | 10.6 † |
| November | 32% | 29% | 69 | 10 °C | 0% | 54% | 8.8 † |
| December | 11% | 28% | 82 | 7 °C | 0% | 80% | 8.0 † |
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 Tienen → Hombourg, km/h | Headwind > 15 km/h, Tienen → Hombourg | Headwind > 15 km/h, Hombourg → Tienen | Better way |
|---|---|---|---|---|
| January | +5.7 | 2% | 20% | Tienen → Hombourg |
| February | +4.0 | 5% | 18% | Tienen → Hombourg |
| March | +3.4 | 6% | 17% | Tienen → Hombourg |
| April | +1.8 | 5% | 11% | either |
| May | +3.5 | 3% | 14% | Tienen → Hombourg |
| June | +4.4 | 1% | 13% | Tienen → Hombourg |
| July | +6.7 | 1% | 17% | Tienen → Hombourg |
| August | +6.0 | 0% | 14% | Tienen → Hombourg |
| September | +3.7 | 2% | 11% | Tienen → Hombourg |
| October | +3.4 | 2% | 13% | Tienen → Hombourg |
| November | +4.3 | 1% | 14% | Tienen → Hombourg |
| December | +5.4 | 2% | 18% | Tienen → Hombourg |
Along the route (sections of about 25 km)
| km | Heading | Tailwind in September, km/h |
|---|---|---|
| 336–361 | E | +4.0 |
| 361–387 | E | +4.0 |
| 387–412 | E | +4.1 |
| 412–437 | SE | +2.9 |
| 437–450 | SE | +3.0 |
Other stages
- Poperinge → Anzegem 116 km
- Anzegem → Halle 112 km
- Halle → Tienen 109 km
- Tienen → Hombourg 114 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.