Groene Gordelroute: clockwise or anticlockwise, and when to ride
The best month for Groene Gordelroute is September: 77% of days were dry in riding hours with highs of 10–30 °C. In September the wind barely favours either way round — under 2 km/h on average (ERA5 2006–2025, daytime 9:00–18:00).
This route is a loop: the two directions are clockwise and anticlockwise.
Weather by month
| Month | Good days | Rain days ≥ 1 mm | Rain, mm | Avg high | Days ≥ 30 °C | Days < 10 °C | Daylight, h |
|---|---|---|---|---|---|---|---|
| January | 8% | 26% | 69 | 6 °C | 0% | 83% | 8.4 † |
| February | 18% | 28% | 60 | 7 °C | 0% | 71% | 9.9 † |
| March | 47% | 25% | 57 | 11 °C | 0% | 43% | 11.7 |
| April | 69% | 21% | 42 | 15 °C | 0% | 15% | 13.8 |
| May | 73% | 26% | 65 | 18 °C | 0% | 2% | 15.5 |
| June | 73% | 25% | 71 | 21 °C | 3% | 0% | 16.5 |
| July | 68% | 27% | 70 | 23 °C | 6% | 0% | 16.1 |
| August | 66% | 28% | 76 | 23 °C | 6% | 0% | 14.5 |
| September | 77% | 22% | 54 | 20 °C | 1% | 0% | 12.5 |
| October | 74% | 22% | 67 | 15 °C | 0% | 6% | 10.6 † |
| November | 38% | 27% | 64 | 10 °C | 0% | 46% | 8.8 † |
| December | 15% | 24% | 72 | 7 °C | 0% | 75% | 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, clockwise, km/h | Headwind > 15 km/h, clockwise | Headwind > 15 km/h, anticlockwise | Better way |
|---|---|---|---|---|
| January | +0.6 | 14% | 16% | either |
| February | +0.4 | 15% | 17% | either |
| March | +0.2 | 12% | 14% | either |
| April | +0.1 | 10% | 10% | either |
| May | +0.2 | 9% | 10% | either |
| June | +0.3 | 8% | 8% | either |
| July | +0.6 | 8% | 9% | either |
| August | +0.5 | 8% | 8% | either |
| September | +0.3 | 9% | 10% | either |
| October | +0.4 | 11% | 13% | either |
| November | +0.5 | 13% | 15% | either |
| December | +0.7 | 14% | 17% | either |
Along the route (sections of about 25 km)
| km | Heading | Tailwind in September, km/h |
|---|---|---|
| 0–25 | NE | +3.8 |
| 25–50 | E | +2.6 |
| 50–76 | S | −3.2 |
| 76–101 | W | −4.2 |
| 101–124 | N | +2.8 |
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.