Tailwind Atlas

Nasjonal sykkelrute 9: which way and when to ride

The best month for Nasjonal sykkelrute 9 is September: 69% of days were dry with highs of 10–30 °C. In September, riding near Halden → Innbygda meant an average tailwind of 3.0 km/h (ERA5 2006–2025, daytime 9:00–18:00).

ERA5 2006–2025 · OpenStreetMap · Methodology and sources

391 kmLength
June, September (peak September)Best months
near Halden → InnbygdaBetter direction in the best month
3.0 km/hAverage tailwind in the best month
69%Dry days with 10–30 °C
June · 67%Best summer month
Start: near Halden · Finish: Innbygda · Route geometry: OpenStreetMap / Waymarked Trails

Weather by month

MonthGood daysRain days ≥ 1 mmRain, mmAvg highDays ≥ 30 °CDays < 10 °CDaylight, h
January0%21%62-2 °C0%100%6.6 †
February0%18%48-1 °C0%100%9.0 †
March9%15%414 °C0%91%11.6
April40%20%4410 °C0%58%14.5
May63%29%7515 °C0%16%17.1
June67%32%8819 °C0%1%18.9
July62%37%11321 °C1%0%18.1
August62%38%11319 °C0%0%15.6
September69%26%8015 °C0%6%12.7
October29%23%779 °C0%62%9.9 †
November3%23%703 °C0%95%7.3 †
December0%23%63-1 °C0%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

MonthWind near Halden → Innbygda, km/hHeadwind > 15 km/h, near Halden → InnbygdaHeadwind > 15 km/h, Innbygda → near HaldenBetter way
January+1.22%8%either
February+1.72%7%either
March+1.43%7%either
April+0.45%5%either
May+1.54%6%either
June+2.33%5%near Halden → Innbygda
July+2.82%4%near Halden → Innbygda
August+3.32%7%near Halden → Innbygda
September+3.02%8%near Halden → Innbygda
October+2.43%8%near Halden → Innbygda
November+1.63%7%either
December+1.72%9%either

Along the route (sections of about 25 km)

kmHeadingTailwind in September, km/h
0–25E+2.5
25–50N+4.0
50–75N+3.2
75–100NE+3.7
100–126N+3.1
126–151NE+2.9
151–177E+2.2
177–202N+3.4
202–227N+3.1
227–252N+3.0
252–278N+3.0
278–303NW+2.3
303–328N+3.0
328–353NW+1.5
353–379N+3.5
379–391NE+3.2

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.

OpenStreetMap · Waymarked Trails