BiH Trebinje, stage 4: Zvornik → Bijeljina
On stage 4 (Zvornik → Bijeljina, 69 km) the best month is October: 81% of days were dry with highs of 10–30 °C; the wind barely favours either direction (0.8 km/h on average; 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 | 21% | 20% | 60 | 5 °C | 0% | 76% | 9.2 † |
| February | 36% | 23% | 57 | 8 °C | 0% | 58% | 10.4 † |
| March | 57% | 23% | 72 | 13 °C | 0% | 31% | 11.8 |
| April | 71% | 25% | 66 | 18 °C | 1% | 8% | 13.4 |
| May | 65% | 31% | 95 | 22 °C | 4% | 1% | 14.8 |
| June | 45% | 32% | 84 | 27 °C | 28% | 0% | 15.5 |
| July | 39% | 22% | 67 | 29 °C | 42% | 0% | 15.2 |
| August | 39% | 17% | 51 | 29 °C | 46% | 0% | 14.0 |
| September | 67% | 21% | 60 | 24 °C | 13% | 0% | 12.4 |
| October | 81% | 16% | 56 | 18 °C | 0% | 7% | 10.9 † |
| November | 55% | 19% | 63 | 12 °C | 0% | 36% | 9.5 † |
| December | 21% | 18% | 64 | 6 °C | 0% | 75% | 8.8 † |
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 Zvornik → Bijeljina, km/h | Headwind > 15 km/h, Zvornik → Bijeljina | Headwind > 15 km/h, Bijeljina → Zvornik | Better way |
|---|---|---|---|---|
| January | −0.1 | 1% | 0% | either |
| February | −0.8 | 1% | 1% | either |
| March | −1.2 | 2% | 2% | either |
| April | −1.5 | 2% | 1% | either |
| May | −1.6 | 1% | 0% | either |
| June | −1.8 | 1% | 0% | either |
| July | −2.1 | 1% | 0% | Bijeljina → Zvornik |
| August | −1.8 | 0% | 0% | either |
| September | −1.5 | 0% | 0% | either |
| October | −0.8 | 1% | 1% | either |
| November | +0.1 | 1% | 1% | either |
| December | +0.1 | 1% | 1% | either |
Along the route (sections of about 25 km)
| km | Heading | Tailwind in October, km/h |
|---|---|---|
| 350–375 | N | −1.7 |
| 375–389 | SW | +1.7 |
| 389–415 | N | −1.2 |
| 415–419 | NW | −0.6 |
Other stages
- Trebinje → Foča 142 km
- Foča → Sokolac 102 km
- Sokolac → Zvornik 102 km
- Zvornik → Bijeljina 69 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.