FAQ & how scoring works

How the downwind score works

Every run gets a 0–100 downwind score for each hour of the forecast. It answers one question: how good is the downwind paddling along this exact line, right now?

The score multiplies two things:

• Alignment — how well the wind is blowing along your run rather than across or against it. We compare the wind's direction to the bearing of each leg of your line and length-weight it, so a run that's dead downwind for most of its length but bends into a crosswind at the end scores high-but-not-perfect — which is the truth.
• Strength — how much wind there is. Below about 6 knots nothing rideable forms, so the score is near zero no matter the direction. It climbs from there and saturates around 22 knots of sustained wind, where most paddlers have plenty to work with.

A score near 100 means strong wind blowing straight down your line. A low score can mean two different things, and the label tells you which:

• Too light — the wind direction may be perfect, but there's not enough of it.
• Off-axis — there's plenty of wind, but it's blowing across or against your run, not down it.
• Marginal → Fun → Good → Raging → Epic — increasing combinations of aligned, strong wind.

What does “best window” mean?

We scan the next 7 days and highlight the longest upcoming stretch where the score stays good, along with its peak. It's the “if you can only go once this week, go then” answer. The full hour-by-hour outlook is right below it if you want to pick your own time.

Where does the data come from?

• Wind, gusts, temperature and the animated wind map — Open-Meteo weather models.
• Waves, swell, tides, currents, sea-surface temperature — Open-Meteo's marine model (resolves on open and coastal water).
• River flow, water temperature, gage height — live USGS river gauges (United States), with a global river-discharge model as a fallback.
• Place search — LocationIQ. Maps — OpenFreeMap / OpenStreetMap.

Forecast data is cached briefly and refreshes through the week as the models update.

The score said 80 but it was mediocre. Why?

The score is only as good as the forecast underneath it, and forecasts are model estimates. A few honest limitations:

• Local effects. Gorge gap winds, thermal sea breezes, headlands and channel funneling can all differ from the broad model — sometimes a lot. Your local knowledge still matters.
• Gusty vs. steady. The score uses sustained wind. A day with the same average but big lulls feels very different on the water.
• Wind isn't everything yet. Today the score is wind-and-direction only. Current against wind (which builds steeper, better bumps) is shown but not yet folded into the number. Some areas tend to have low sustained wind with higher gusts in the forecasts that still produce great waves.
• Local knowledge. We are in the process of tweaking the models and verifying the results on the water. This takes time, the right weather conditions, and people at the specific locations.

Treat the score as a strong starting point, not gospel — and always look at the actual conditions before you launch.

Featured runs vs. my runs

Featured runs are curated classics, fine-tuned point by point. Your runs are ones you trace on the map yourself — start, finish, and any bends. Both are scored exactly the same way. You can rename your runs, edit their points by dragging, and delete them.

Why does an ocean run not show river data (and vice versa)?

River gauges measure streams and rivers; they're meaningless out at sea. So when a point has marine data (waves, tide, current) we treat it as open water and hide nearby river gauges, and inland river runs show the river instead of empty marine fields. Water temperature comes from whichever source fits — sea-surface temperature on the ocean, the gauge on a river.

Can I change the units?

Yes — the Units control on the map switches wind (kn / mph / km·h), temperature (°C / °F), and distance (km / mi) independently, and remembers your choice on that device.

Do my runs sync between devices?

Not yet. Right now your runs and unit preferences are saved in your browser on the device you created them on, so clearing your browser data removes them and they don't follow you to another device. Accounts with synced runs are on the roadmap.

Is it free?

Yes, today. If that changes we'll make it clear well in advance.

A note on safety

Downwinding is a committed, one-way trip, often in conditions where self-rescue is hard. DownwinderApp is a planning aid, not a safety device or navigation tool. Check the real conditions, tell someone your plan, carry what you need, and paddle within your ability. When in doubt, don't go out! See our Terms for the full disclaimer.