GFS vs ICON
GFS or ICON: which is better for Europe?
ICON is Germany's global model and is built with Europe in mind, with a nested higher-resolution European version. GFS is the American global model with a longer range. For a European passage, many sailors look at ICON next to ECMWF and keep GFS for the long view.
| GFS | ICON | |
|---|---|---|
| Provider | NOAA / NCEP | DWD |
| Type | Global model | Global model |
| Area | Global | Global |
| Grid size | about 13 km | about 13 km |
| Updates | 4 times a day | 4 times a day |
| Looks ahead | 16 days | 8 days |
| Data licence | Public domain (US Government) | CC-BY-4.0 (DWD open data) |
Choose GFS when
- You want the longest range of the two (16 days vs about 7).
- You are outside Europe, where GFS is as good a fit as any.
- You need a free, public-domain source with no conditions.
Choose ICON when
- You are sailing in Europe and want a model tuned to it.
- You want a regional ICON-EU or ICON-D2 follow-up for the near term.
- You want to check GFS against a second European-built model.
On the water
Within about a week, ICON and GFS are close in grid size. The deciding factor is usually your sea area and how far ahead you are looking.
Figures come from the Ilma catalog and the providers' own pages. Forecast skill changes as models are upgraded, so this page describes what each model is built for, not a ranking.