A weather model is a computer simulation of the atmosphere on a grid. Global models such as ECMWF IFS, GFS and ICON cover the whole planet with grid spacing of about 9–13 km. Regional models such as ICON-D2, UKV, AROME and HRRR cover one area at 1.3–3 km and update more often. Altiwind uses a regional model where a good one exists, ECMWF IFS everywhere else, and checks the result against nearby airport observations.
The models at a glance
| Model | Run by | Area | Grid spacing | New run | Forecast range |
|---|---|---|---|---|---|
| IFS | ECMWF | global | about 9 km | 4 a day | up to 15 days |
| GFS | NOAA (NCEP) | global | about 13 km | 4 a day | up to 16 days |
| ICON | DWD (Germany) | global | about 13 km | 4 a day | up to 180 hours |
| ICON-D2 | DWD | Germany, Benelux, Switzerland, Austria and parts of neighbours | 2.2 km | every 3 hours | 48 hours |
| UKV | Met Office | UK and Ireland | 1.5 km (published on a 2 km grid) | every hour | 12 hours to 5 days, by run |
| AROME | Météo-France | France and neighbouring areas | 1.3 km | every 3 hours | about 2 days |
| HRRR | NOAA | contiguous US | 3 km | every hour | 18 hours, 48 hours every 6 hours |
Figures are from each centre's documentation and Open-Meteo's model pages, checked October 2026. Centres upgrade their models regularly, so details change.
Global models
- ECMWF IFS. The European Centre for Medium-Range Weather Forecasts runs its Integrated Forecasting System at about 9 km, with main runs at 00 and 12 UTC and shorter runs at 06 and 18 UTC.
- GFS. NOAA's Global Forecast System runs at 13 km, four times a day, out to 16 days.
- ICON. Germany's weather service, DWD, runs ICON globally at about 13 km, four times a day: 180 hours ahead from the 00 and 12 UTC runs, 120 hours from 06 and 18 UTC.
Global models give a consistent picture everywhere and reach a week or more ahead. Their weakness is detail: a 9 km grid box is 81 km², so a single valley, a coastline bend or an afternoon shower is blurred into the average.
Regional models
- ICON-D2 (DWD). 2.2 km over Germany and its neighbours, with a new 48-hour forecast every 3 hours.
- UKV (Met Office). 1.5 km over the UK and Ireland inside a coarser 4 km outer zone. It runs every hour; the 03 and 15 UTC runs reach 120 hours, several others 54 hours, and the rest 12 hours.
- AROME (Météo-France). 1.3 km over mainland France, built for local, fast-changing weather such as storms and fog.
- HRRR (NOAA). 3 km over the contiguous US, updated every hour, with radar data fed in every 15 minutes.
At ICON-D2's resolution, DWD notes, thunderstorm cells can be simulated at least approximately, instead of being estimated as in coarser models. NOAA describes the 3 km HRRR as "convection-allowing" for the same reason.
What resolution means
Grid spacing is the distance between the points where the model calculates the weather. Each value is an average for its box.
- A model needs several grid boxes to show a feature properly. A 2 km model can see large valleys, coastlines and sea breezes; a 13 km model mostly cannot.
- No model sees your hedge, your tree line or the building next to your take-off spot. Local gusts and shelter are always on top of the forecast.
- Finer is not automatically better at a single point. A sharp forecast that puts a shower 10 km too far east can score worse at your spot than a smoother one.
Update cycles and forecast range
Each run starts from a snapshot of recent observations, then steps the atmosphere forward in time. More frequent runs catch changes sooner. That is why hourly models like HRRR and UKV are useful for today, while global models carry the forecast into next week.
The trade-off is range: regional models stop after a day or two, global ones go much further. Forecasts also get less certain the further ahead they look, whichever model you use.
How Altiwind chooses
Altiwind gets its forecasts from Open-Meteo (CC BY 4.0) and picks a model by region:
| Region | Model |
|---|---|
| Central Europe | DWD ICON-D2 |
| UK | Met Office UKV 2 km |
| France | Météo-France AROME |
| United States | NOAA HRRR |
| Everywhere else, and days beyond the regional model's range | ECMWF IFS |
The regional models resolve terrain, coasts and showers better, which matters for wind at drone heights. When their range runs out, ECMWF IFS takes over. Models give wind at 10, 80, 120 and 180 m above ground, and Altiwind interpolates between those levels for 30, 60, 90 and 120 m; see wind at altitude.
Checking models against METARs
Every model has local habits. One may run a little windy at a coastal airport, another a little calm in a valley. Altiwind's verified badge measures this:
- It reads the last 6–24 hours of wind and gusts from the nearest airport METAR within 25 km.
- It compares them with 2–3 models for the same hours.
- It picks the model with the smallest error for that area and shows the bias, for example "Checked vs EGLL 40 min ago: running 3 km/h high".
The airport is not your exact spot, and METARs are measured at 10 m, but a recent check against real observations is a strong hint about how far to trust the numbers today. See verified forecast, and our guide to reading METARs.
Sources
- ECMWF, Medium-range forecasts
- NOAA EMC, Global Forecast System (GFS)
- DWD, NWP forecast data (ICON, ICON-EU, ICON-D2)
- Met Office, Numerical weather prediction models (UKV)
- Météo-France, Les modèles de prévision météo (AROME)
- NOAA, High-Resolution Rapid Refresh (HRRR)
- Open-Meteo model documentation for ECMWF, DWD, UK Met Office, Météo-France and NOAA
FAQ
Which weather model is most accurate for drone flying?
There is no single winner. Accuracy depends on the place, the season and the weather pattern. That is why Altiwind uses regional models where they exist and checks models against the nearest airport.
What does "2 km resolution" mean?
The model calculates the weather on points about 2 km apart, and each value is an average for its grid box. Features smaller than a few boxes, like a single hill or street, are not resolved.
Why does my forecast change between runs?
Each run starts from newer observations. Small changes in the starting point can shift the timing of a front or a shower, especially a day or more ahead.
Why does Altiwind switch to ECMWF after a day or two?
Regional models only run a day or two ahead. After that, Altiwind uses ECMWF IFS, a global model with a long range.