South by Cycle bikepacking route: which way and when to ride
The best month for South by Cycle bikepacking route is June: 80% of days were dry with highs of 10–30 °C. In June, riding Hanko → near Lohja meant an average tailwind of 5.3 km/h (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 | 0% | 22% | 56 | -1 °C | 0% | 100% | 6.7 † |
| February | 0% | 20% | 44 | -1 °C | 0% | 100% | 9.0 † |
| March | 1% | 15% | 36 | 2 °C | 0% | 99% | 11.6 |
| April | 20% | 15% | 37 | 7 °C | 0% | 79% | 14.5 |
| May | 67% | 16% | 38 | 13 °C | 0% | 24% | 17.1 |
| June | 80% | 20% | 52 | 18 °C | 0% | 1% | 18.8 |
| July | 77% | 23% | 64 | 21 °C | 0% | 0% | 18.1 |
| August | 74% | 26% | 78 | 20 °C | 0% | 0% | 15.6 |
| September | 73% | 23% | 62 | 15 °C | 0% | 5% | 12.7 |
| October | 35% | 24% | 71 | 9 °C | 0% | 50% | 10.0 † |
| November | 4% | 24% | 64 | 5 °C | 0% | 95% | 7.4 † |
| December | 0% | 25% | 64 | 2 °C | 0% | 100% | 5.9 † |
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 Hanko → near Lohja, km/h | Headwind > 15 km/h, Hanko → near Lohja | Headwind > 15 km/h, near Lohja → Hanko | Better way |
|---|---|---|---|---|
| January | +3.0 | 10% | 22% | Hanko → near Lohja |
| February | +2.8 | 8% | 18% | Hanko → near Lohja |
| March | +3.4 | 9% | 21% | Hanko → near Lohja |
| April | +3.2 | 8% | 18% | Hanko → near Lohja |
| May | +3.8 | 8% | 17% | Hanko → near Lohja |
| June | +5.3 | 6% | 21% | Hanko → near Lohja |
| July | +4.8 | 5% | 20% | Hanko → near Lohja |
| August | +4.8 | 7% | 21% | Hanko → near Lohja |
| September | +4.2 | 8% | 22% | Hanko → near Lohja |
| October | +4.5 | 9% | 25% | Hanko → near Lohja |
| November | +4.1 | 10% | 23% | Hanko → near Lohja |
| December | +5.2 | 8% | 27% | Hanko → near Lohja |
Along the route (sections of about 25 km)
| km | Heading | Tailwind in June, km/h |
|---|---|---|
| 0–25 | NE | +7.7 |
| 25–50 | N | +3.9 |
| 50–76 | NE | +6.4 |
| 76–101 | E | +4.3 |
| 101–128 | NE | +4.6 |
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.