Weather models, explained.
A weather model is a computer simulation of the atmosphere. Each uses different maths, input data, and resolution. No single model is best everywhere — the trick is knowing which to trust for your area and time-frame.
Which model where.
Most sailors don't need to swap between ten models. Pair one global long-range with one regional short-range and you've covered the work.
Mediterranean
ECMWF for the 5-day outlook, then ICON or AROME inside 48 hours. AROME catches the land/sea breezes and katabatic winds GFS misses entirely on the Croatian and Greek coasts.
Atlantic & offshore
ECMWF is king — consistently better than GFS on synoptic-scale systems (lows, fronts, trades). When they disagree significantly, respect the ECMWF and consider waiting for the next run.
UK & Northern Europe
ICON for 0–3 day coastal forecasts — it handles the North Sea and English Channel complexity well. Fall back to ECMWF for longer range.
Caribbean & US coast
GFS and NAM are your defaults; HRRR for day-of conditions with hourly updates. For hurricanes, always cross-reference the NHC official — never a single model.
Five tips most sailors miss.
- 01
Compare at least two models.
If GFS says 15 kn and ECMWF says 30, don't split the difference. Work out why they disagree and prepare for the worse case.
- 02
Use the Waves layer for swell.
Wind speed alone doesn't tell you sea state. A 15-knot breeze against a 2 m leftover swell makes for a miserable sea.
- 03
Open the meteogram view.
Tap any point and read it as a time-series — wind, gusts, rain, pressure, temperature in one chart. Much easier to spot weather windows.
- 04
Set alerts for your route.
Premium lets you set thresholds at specific locations. Set them at departure, waypoints, and destination.
- 05
Pressure isobars tell the real story.
Tightly packed isobars mean strong wind. If you see them squeezing over the next few days, find a sheltered anchorage.
Free vs Premium.
Free
- ·GFS, ICON, and other free models
- ·3-hourly forecast data
- ·Wind, rain, temperature, pressure layers
- ·Meteograms and point forecasts
- ·Wave and swell data
Premium · ~$20 / yr
- ·ECMWF, AROME, NEMS, premium models
- ·1-hourly forecast resolution
- ·Weather alerts for saved locations
- ·Better hurricane / storm tracking
- ·Ad-free
For serious sailing, Premium is worth it. ECMWF access alone justifies the cost — it's the model professional forecasters trust most.