BoatCast
How BoatCast works
Transparent rules for Good, Fair, and Poor — so you can decide whether to trust the rating. Last updated August 21, 2026.
BoatCast combines forecast data and boating-focused rules to turn several conditions into one easy-to-understand rating. The website map is included with BoatCast Pro; the same scoring is documented here for anyone using the mobile app or deciding whether to subscribe.
BoatCast is provided for general informational and planning purposes only. It is not a substitute for official weather and marine forecasts, observations, alerts, watches, warnings, advisories, notices, or instructions from NOAA, the National Weather Service, the U.S. Coast Guard, emergency authorities, or other official sources. Always review current official information and actual local conditions before and during any boating activity.
When an official warning is active near your pin, BoatCast surfaces it prominently even if some model inputs look favorable. Full text: Forecast & Safety Disclaimer.
What the rating represents
- The rating is for the weather zone around your selected point (about a 10-mile grid cell), not every cove or channel inside that zone.
- Day cards (Today / Tonight / later days) vote remaining hourly conditions in that card’s time window.
- Overall hour rating uses the worst limiting factor among weather, wind, visibility, waves/swell, and (when seas are not flat) wave period.
Inputs that affect the rating
- Sky / precip: drizzle and fog tend toward Fair; rain, snow, and thunderstorms rate Poor. Thunderstorms also include rain/shower hours with high CAPE (≥ 1000 J/kg) when the model does not emit an explicit storm code.
- Wind: By default, Good under 15 mph, Fair 15–25 mph, Poor over 25 mph (sustained). Pro subscribers can save a boat size to use knot-based bands instead (small ≈ under 10 kt Good; medium ≈ under 15 kt; large ≈ under 20 kt, with Fair up to the next step).
- Visibility: Good above 5 nautical miles, Fair 2–5 NM, Poor under 2 NM (NWS/IMO-style bands). Period cards use the minimum visibility in the window.
- Waves / chop: By default, height is scored against regional typical wave height (coastal regions differ; lakes use Great Lakes–style norms). Roughly within ~1× typical is Good; much higher becomes Fair then Poor. With a Pro boat size selected, height bands use both boat-size comfort floors and regional typical seas (so West Coast swell near local averages is not always Poor for a small boat), while wave-period scoring still uses area norms (stricter short-period slack for smaller boats).
- Swell: scored on ocean / coastal points; skipped for lake source.
- Wave period: compared to regional typical bands (for example Southeast Atlantic ~4–8s, Southern California ~8–14s). Periods shorter than the band can rate Fair/Poor (“short-period chop”). Flat seas under ~0.15 m skip period scoring. Longer-than-typical period is treated as Good.
- Gusts, rain chance, clouds, feels-like: shown in detail views; they inform the picture but the headline rating is driven by the factors above.
Rating master matrix
Each hour (and period/day vote) takes the worst factor among the rows below. Generic = free plan / Pro with No Selection. Boat-size rows are Pro preferences. Wave/swell boat floors can rise on energetic coasts (larger of the absolute band and a share of local typical height).
Same for every boat size (including generic)
| Factor | Good | Fair | Poor |
|---|---|---|---|
| Sky / precip | Clear / mostly clear / cloudy / overcast (no limiting precip) | Fog or drizzle | Rain, showers, snow, thunderstorms (WMO 95/96/99, or rain/shower + CAPE ≥ 1000 J/kg) |
| Visibility | > 5 NM | 2–5 NM | < 2 NM |
| Official alerts | No blocking NWS product overlapping the hour | Blocking watch/warning/advisory overlapping the hour → force Poor | |
| Not in headline rating | Gusts, precip %, cloud cover, feels-like, tides, sun/moon, solunar — detail UI only | ||
Wind, waves / swell, and period by size
| Size | Factor | Good | Fair | Poor |
|---|---|---|---|---|
| Generic | Wind | < 15 mph | 15–25 mph | > 25 mph |
| Waves / swell | ≤ ~1.05× local typical | ≤ ~1.7× local typical | > ~1.7× local typical | |
| Wave period | ≥ regional min (e.g. SoCal 8s+); longer OK | Somewhat short of regional min (wider slack) | Well short of regional min | |
| Small6–16 ft | Wind | ≤ 10 kt | ≤ 15 kt | > 15 kt |
| Waves / swell | ≤ max(1.5 ft, 55% of typical) | ≤ max(2.5 ft, 90% of typical) | Above Fair cap | |
| Wave period | ≥ regional min | Short of min (tightest slack) | Well short (chop) | |
| Medium16–26 ft | Wind | ≤ 15 kt | ≤ 20 kt | > 20 kt |
| Waves / swell | ≤ max(2.5 ft, 95% of typical) | ≤ max(3.5 ft, 145% of typical) | Above Fair cap | |
| Wave period | ≥ regional min | Short of min (mid slack) | Well short (chop) | |
| Large26+ ft | Wind | ≤ 20 kt | ≤ 25 kt | > 25 kt |
| Waves / swell | ≤ max(5 ft, 135% of typical) | ≤ max(7 ft, 190% of typical) | Above Fair cap | |
| Wave period | ≥ regional min | Short of min (widest slack) | Well short (chop) |
Period scoring is skipped when seas are essentially flat (< ~0.15 m). Swell is skipped in lake mode. Example local typicals: Southern California ~3.6 ft waves / 8–14s; Gulf ~2.3 ft / 3–5s; Great Lakes ~1.6 ft / 2–5s. Day cards also apply majority-hour vote rules (including thunderstorm stretch overrides) on top of per-hour scores.
Lakes vs coastal water
If Open-Meteo Marine has wave/swell at the pin, BoatCast treats the spot as ocean. Otherwise it uses lake mode: wind-based chop estimates and lake water-temperature methods (satellite SST when available, otherwise regional shore-air memory). Swell is not scored on lakes.
How wind direction relates to chop
Lake chop height is estimated from wind speed (and related marine fields when present). Direction is shown so you can judge fetch and lee shores yourself; the automated rating does not yet model shoreline-specific wind waves for every cove.
Update frequency
- Assembled BoatCast forecasts are cached about 45 minutes per weather zone.
- Underlying Open-Meteo air/marine bundles may be reused up to about an hour.
- Live radar at the pin refreshes on a shorter cadence (~3 minutes) for the Now card.
- Official NWS alerts are checked separately on a short cache (~3 minutes).
The day card shows when BoatCast last built the forecast for that zone (“Forecast updated … ago”). These caches are not a personal location history.
Why BoatCast may differ from NOAA, Windy, or another app
- Different model grids and blend choices (Open-Meteo vs NWS grids).
- BoatCast collapses many variables into one recreational-boating score with fixed thresholds — other apps emphasize different hazards.
- Zone averaging (~10 mi) can miss microclimates, passes, and river mouths.
- Lake water temperature and chop are estimates when dedicated marine fields are missing.
What “AI” means here
BoatCast uses automated rules and model outputs — not a black-box “AI says go” judgment. Marketing may mention AI-assisted tooling in development; the rating you see is deterministic from the published thresholds above. We do not claim to be the most accurate weather source without published verification studies.
Data sources
- Weather forecast: Open-Meteo
- Marine / water: Open-Meteo Marine when wave/swell is available; otherwise Open-Meteo air plus wind-based lake estimates
- Water temperature (when used): NOAA GLSEA, JPL MUR, Copernicus LSWT, or regional shore-air / model estimate
- Map / places: OpenStreetMap Nominatim
- Radar: RainViewer
- Official alerts: National Weather Service (api.weather.gov)
Accounts, Pro, and sync
- The free forecast works without signing in.
- On iOS and Android, Pro is an App Store / Play purchase. Favorites and boat size work on this phone without a BoatCast account.
- Prefer signing in with Apple, Google, or email first (creates your BoatCast account if you are new), then subscribe with Apple on iPhone, Google Play on Android, or Stripe on the website. You can also subscribe first on mobile without an account, then sign in to sync Pro and saved places. Hide My Email still uses Sign in with Apple on every device (we match your Apple ID). A different email later is a different user and will not carry those favorites.
- Web Stripe checkout uses the email entered in Stripe as the BoatCast account, then asks you to set a password. Location Weather Monitoring also needs sign-in (email and push). Live GPS monitoring uses background location only while a session is on; a fixed pin does not.
Boat-size ratings (Pro)
Pro can save Small (6–16 ft), Medium (16–26 ft), Large (26+ ft), or No Selection under Account → Boat Size (also from the day rating card). On iOS/Android that preference can stay on this device without an account; it syncs to your BoatCast account when you sign in. Storm / weather-code Poor ratings, visibility, and official alerts stay the same; only wind, waves/swell, and short-period chop tighten or relax to match the boat. Location Weather Monitoring uses the same saved preference when scoring Today/Tonight changes.
Location Weather Monitoring (Pro)
Pro subscribers can ask BoatCast to watch a selected map pin on web or mobile, or their live GPS position on mobile, for a limited window (rest of the current morning / afternoon / evening / night, rest of the day, or until a chosen time). Monitoring needs a BoatCast sign-in so we can email your account address and/or send a mobile push. Live GPS (Monitor My Location) uses Always / background location only while that session is on — not for ads, and not as a location history. A fixed pin does not need background location. The server periodically re-fetches the same forecast rules used in the app. If Today’s or Tonight’s majority rating changes, or a new NWS alert appears for that spot, BoatCast notifies you. Only one monitoring session runs at a time.
Questions or a rating that looks wrong? Report a forecast or email boatcastapp@gmail.com.
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