37: which way and when to ride
The best month for 37 is September: 78% of days were dry with highs of 10–30 °C. In September the wind barely favours either direction — on average 2.0 km/h along the route (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 | 2% | 20% | 46 | 2 °C | 0% | 98% | 8.6 † |
| February | 7% | 17% | 35 | 4 °C | 0% | 91% | 10.0 † |
| March | 32% | 21% | 42 | 8 °C | 0% | 64% | 11.7 |
| April | 61% | 24% | 45 | 14 °C | 0% | 26% | 13.7 |
| May | 65% | 32% | 75 | 17 °C | 0% | 5% | 15.4 |
| June | 68% | 29% | 73 | 22 °C | 4% | 0% | 16.3 |
| July | 63% | 30% | 78 | 24 °C | 8% | 0% | 15.9 |
| August | 65% | 27% | 80 | 23 °C | 9% | 0% | 14.4 |
| September | 78% | 22% | 59 | 19 °C | 0% | 2% | 12.5 |
| October | 60% | 19% | 46 | 13 °C | 0% | 27% | 10.6 † |
| November | 17% | 18% | 44 | 6 °C | 0% | 80% | 9.0 † |
| December | 2% | 18% | 46 | 3 °C | 0% | 97% | 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 Eslarn → Broumy, km/h | Headwind > 15 km/h, Eslarn → Broumy | Headwind > 15 km/h, Broumy → Eslarn | Better way |
|---|---|---|---|---|
| January | +6.4 | 2% | 26% | Eslarn → Broumy |
| February | +4.4 | 5% | 21% | Eslarn → Broumy |
| March | +2.9 | 6% | 19% | Eslarn → Broumy |
| April | +0.2 | 6% | 10% | either |
| May | +0.3 | 7% | 10% | either |
| June | +1.8 | 3% | 9% | either |
| July | +4.5 | 1% | 14% | Eslarn → Broumy |
| August | +3.5 | 1% | 9% | Eslarn → Broumy |
| September | +2.0 | 3% | 10% | either |
| October | +3.6 | 2% | 15% | Eslarn → Broumy |
| November | +4.7 | 2% | 19% | Eslarn → Broumy |
| December | +6.9 | 2% | 25% | Eslarn → Broumy |
Along the route (sections of about 25 km)
| km | Heading | Tailwind in September, km/h |
|---|---|---|
| 0–25 | NE | +1.8 |
| 25–50 | NE | +1.9 |
| 50–75 | NE | +1.9 |
| 75–101 | E | +2.3 |
| 101–126 | NE | +2.0 |
| 126–151 | NE | +2.0 |
| 151–154 | N | +0.7 |
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.