How it works
A weather app tells you what the sky is doing at home. Velvind answers a different question: what will the sky be doing where you are, when you get there — for every kilometre of a ride that moves. Here is the derivation, start to verdict.
01
Your route, every 250 metres
Whatever you bring in — a Strava route, a GPX, TCX or FIT file, a line drawn on the map, a link a friend shared — Velvind resamples it into evenly spaced points, one every 250 metres. Each point carries its distance, elevation, the grade of the road under it, and the compass bearing you'll be riding on. That bearing is what makes wind mean something later. Climbing, meanwhile, is counted from the raw elevation profile rather than the smoothed resample, so the headline metres agree with your head unit instead of flattering you.
02
Timing that respects the climbs
A flat 25 km/h says nothing about a 9% ramp. Velvind walks the route point by point with a grade-adjusted pace model anchored to the flat speed you set: climbs slow you down exponentially with the gradient, descents speed you up — capped at 65 km/h, because nobody forecasts well at terminal velocity — and any stops you add are inserted at their distance along the way. The result is an honest arrival time for every point on the route, not just the finish line.
03
One forecast per patch of sky
The route is reduced to weather cells about 11 km across (a 0.1° grid), and Velvind fetches an hourly forecast for each cell from Open-Meteo — up to 16 days ahead. Because each cell arrives as a complete hourly series rather than a single answer, the forecast doesn't care when you leave. Change the departure or the pace and the whole plan re-derives instantly, with zero new network requests.
04
Weather at the hour you arrive
For every point, Velvind reads the forecast at that point's arrival time, interpolating between the two bracketing hours. Wind gets special care: it is interpolated as a vector, so a breeze swinging through north between 09:00 and 10:00 never averages into a direction from nowhere. This is the difference between "today: wind from the west" and the wind you'll actually meet at km 60.
05
Wind, resolved against you
A 20 km/h westerly is a fact; whether it's a friend depends on which way you're pointed. Each point's wind is resolved against your travel bearing into a headwind and a crosswind component, then classified — head, cross or tail. That's the tricolore you see along the route: green for tailwind, stone for calm, coral for the stretch you'll spend fighting it.
06
Daylight from sun geometry
Sunrise, sunset, civil dawn and dusk, golden hour — computed from the sun's actual geometry for the day and place you're riding, then laid against your arrival times. If the ride crosses sunset, Velvind tells you when you'll need lights — not as a vibe, as a clock time.
07
The kindest start
Ask, and Velvind re-runs the entire derivation for dozens of candidate departures across your day — scoring each by the headwind it incurs (headwind counts against you harder than tailwind counts for you) and the distance ridden in likely rain, while tracking how much of the ride falls in the dark. The same scan runs across the coming days to answer "is Sunday kinder than today?". It all reuses the forecasts already in hand, so scanning a whole day costs nothing and answers instantly.
Questions riders ask
Which forecast does Velvind use?
Open-Meteo, at hourly resolution. Velvind doesn't average your day into one icon — it reads the exact hours you'll be out, point by point along the route.
How far ahead can I plan?
Up to 16 days out — the forecast horizon. Beyond a few days, treat it as a trend rather than a promise; the day scan exists precisely to compare candidate days as the picture firms up.
Does it work for gravel rides?
Yes. Velvind classifies your route from OpenStreetMap data into paved, gravel and path, and shows the mix. Wind, rain, temperature and daylight work the same whatever you ride.
How do I get a route in?
Sync from Strava, upload a GPX, TCX or FIT file, draw directly on the map, or open a link a friend shared.
How accurate are the arrival times?
As good as the flat speed you give it. From there the pace model does the honest work: climbs slow you down with the gradient, descents are capped at 65 km/h, and stops you add are counted at their place on the route.
Is it free?
Yes. You sign in — with email or Google — so your routes and plans have somewhere to live, and that's the whole price.