Mittelland-Route (Aachen – Zittau), stage 2: Bonn → Siegen
On stage 2 (Bonn → Siegen, 131 km) the best month is September: 76% of days were dry with highs of 10–30 °C, and riding Bonn → Siegen meant an average tailwind of 3.0 km/h (ERA5 2006–2025, 9:00–18:00).
← Mittelland-Route (Aachen – Zittau) (Whole route)
Weather by month
| Month | Good days | Rain days ≥ 1 mm | Rain, mm | Avg high | Days ≥ 30 °C | Days < 10 °C | Daylight, h |
|---|---|---|---|---|---|---|---|
| January | 3% | 34% | 104 | 4 °C | 0% | 92% | 8.4 † |
| February | 10% | 31% | 78 | 5 °C | 0% | 85% | 9.9 † |
| March | 34% | 30% | 76 | 9 °C | 0% | 58% | 11.7 |
| April | 62% | 25% | 55 | 14 °C | 0% | 24% | 13.8 |
| May | 67% | 32% | 83 | 18 °C | 0% | 4% | 15.5 |
| June | 68% | 29% | 81 | 21 °C | 3% | 0% | 16.5 |
| July | 61% | 31% | 87 | 23 °C | 9% | 0% | 16.1 |
| August | 64% | 29% | 90 | 23 °C | 7% | 0% | 14.5 |
| September | 76% | 23% | 71 | 19 °C | 1% | 0% | 12.5 |
| October | 61% | 27% | 81 | 14 °C | 0% | 17% | 10.6 † |
| November | 21% | 32% | 86 | 8 °C | 0% | 68% | 8.8 † |
| December | 5% | 35% | 109 | 5 °C | 0% | 89% | 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 Bonn → Siegen, km/h | Headwind > 15 km/h, Bonn → Siegen | Headwind > 15 km/h, Siegen → Bonn | Better way |
|---|---|---|---|---|
| January | +4.9 | 2% | 19% | Bonn → Siegen |
| February | +3.2 | 5% | 17% | Bonn → Siegen |
| March | +2.8 | 5% | 15% | Bonn → Siegen |
| April | +1.6 | 5% | 9% | either |
| May | +2.4 | 3% | 10% | Bonn → Siegen |
| June | +3.5 | 1% | 9% | Bonn → Siegen |
| July | +5.8 | 0% | 13% | Bonn → Siegen |
| August | +4.9 | 0% | 10% | Bonn → Siegen |
| September | +3.0 | 2% | 9% | Bonn → Siegen |
| October | +3.0 | 2% | 11% | Bonn → Siegen |
| November | +3.4 | 2% | 13% | Bonn → Siegen |
| December | +4.5 | 2% | 16% | Bonn → Siegen |
Along the route (sections of about 25 km)
| km | Heading | Tailwind in September, km/h |
|---|---|---|
| 136–162 | NE | +3.1 |
| 162–187 | E | +2.5 |
| 187–212 | E | +3.2 |
| 212–237 | E | +2.9 |
| 237–262 | E | +3.5 |
| 262–267 | NE | +3.1 |
Other stages
- Aachen → Bonn 137 km
- Bonn → Siegen 131 km
- Siegen → Stadtallendorf 110 km
- Stadtallendorf → Heringen 116 km
- Heringen → Erfurt 118 km
- Erfurt → Gera 115 km
- Gera → Freiberg 124 km
- Freiberg → Neustadt in Sachsen 115 km
- Neustadt in Sachsen → Zittau 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.