Nasjonal sykkelrute 1 (Alta – Tromsø): which way and when to ride
The best month for Nasjonal sykkelrute 1 (Alta – Tromsø) is July: 60% of days were dry with highs of 10–30 °C. In July the wind barely favours either direction — on average 0.8 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 | 0% | 26% | 76 | -6 °C | 0% | 100% | 0.0 † |
| February | 0% | 29% | 72 | -6 °C | 0% | 100% | 7.1 † |
| March | 0% | 31% | 85 | -3 °C | 0% | 100% | 11.3 |
| April | 1% | 33% | 78 | 1 °C | 0% | 99% | 15.9 |
| May | 16% | 34% | 80 | 6 °C | 0% | 80% | 22.1 |
| June | 37% | 42% | 99 | 11 °C | 0% | 44% | 24.0 |
| July | 60% | 33% | 96 | 15 °C | 0% | 13% | 24.0 |
| August | 57% | 35% | 93 | 14 °C | 0% | 16% | 18.0 |
| September | 35% | 36% | 95 | 10 °C | 0% | 53% | 13.1 |
| October | 4% | 34% | 90 | 3 °C | 0% | 96% | 8.7 † |
| November | 0% | 29% | 75 | -2 °C | 0% | 100% | 3.5 † |
| December | 0% | 28% | 78 | -4 °C | 0% | 100% | 0.0 † |
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 Alta → Tromsø, km/h | Headwind > 15 km/h, Alta → Tromsø | Headwind > 15 km/h, Tromsø → Alta | Better way |
|---|---|---|---|---|
| January | −0.2 | 2% | 1% | either |
| February | −0.4 | 2% | 1% | either |
| March | −1.8 | 2% | 0% | either |
| April | −1.5 | 2% | 1% | either |
| May | −1.1 | 3% | 1% | either |
| June | −1.8 | 3% | 1% | either |
| July | −0.8 | 2% | 1% | either |
| August | −0.8 | 2% | 1% | either |
| September | −1.1 | 2% | 1% | either |
| October | −0.7 | 1% | 1% | either |
| November | −0.4 | 2% | 1% | either |
| December | −0.4 | 2% | 1% | either |
Along the route (sections of about 25 km)
| km | Heading | Tailwind in July, km/h |
|---|---|---|
| 0–25 | NW | −0.8 |
| 25–51 | NW | −0.6 |
| 51–77 | W | −1.4 |
| 77–103 | SW | +0.2 |
| 103–128 | W | −1.7 |
| 128–153 | W | −0.9 |
| 153–178 | W | −0.5 |
| 178–203 | SW | +0.4 |
| 203–229 | SW | −1.1 |
| 229–254 | NW | −1.0 |
| 254–280 | SW | −0.4 |
| 280–305 | NW | −1.5 |
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.