Is the European model (ECMWF) always more accurate than the GFS?

No. Over long verification records the ECMWF tends to score highest for global medium-range accuracy, which is why it is often called the best model. But it is not always right. On individual storms, regions or short-range forecasts the American GFS regularly matches or beats it, so forecasters treat both as valuable rather than crowning one permanent winner.

Why does the GFS update more often than ECMWF?

The GFS runs four full cycles a day at 00, 06, 12 and 18 UTC, while ECMWF's flagship high-resolution forecast has traditionally centred on two main runs at 00 and 12 UTC. More frequent GFS runs mean it can pick up new observations and shifts a little sooner, though frequency alone does not decide which forecast is correct.

Is ECMWF data still expensive or paywalled?

Much less than it used to be. ECMWF began releasing an open subset of real-time forecasts in 2022, and from October 2025 it opened its entire real-time catalogue for free at 25 km resolution with no delay. The very highest-resolution 9 km products still involve licensing for some professional users, but core forecast data is now openly available.

What made ECMWF famous with Hurricane Sandy?

In October 2012 the ECMWF forecast Sandy's sharp northwest turn back into the US East Coast six to seven days ahead, while the GFS kept the storm heading out to sea. ECMWF was correct, giving forecasters crucial extra warning. Studies later traced the difference mainly to how each model handled convection, not just resolution.

Guides›The European model vs the American model: ECMWF vs GFS

The European model vs the American model: ECMWF vs GFS

Two global supercomputer models drive most of the world's forecasts. Here is how the European ECMWF and the American GFS actually differ, and why neither one is always right.

Two models, one planet

Almost every weather forecast you see starts with a global model: a giant physics simulation of the entire atmosphere, run on a supercomputer. Two of these models dominate the field. One is European, one is American, and professional forecasters watch both of them, every single day.

The European model is usually called the ECMWF, after the European Centre for Medium-Range Weather Forecasts that runs it. The American model is the GFS, the Global Forecast System, run by the United States agency NOAA. They solve the same physics over the same planet, yet they often disagree. Understanding why is the key to reading any forecast honestly.

ECMWF: the European heavyweight

ECMWF's flagship high-resolution forecast, produced by its Integrated Forecasting System (IFS), runs at roughly 9 km grid spacing. In other words, the model chops the globe into boxes about 9 km across. That is a finer grid than the American model uses, and it is one reason the European system has topped global accuracy rankings for years.

ECMWF is an independent intergovernmental organisation backed by more than 30 European member and cooperating states, based in Reading in the UK with a data centre in Bologna, Italy. Its headline high-resolution forecast has traditionally been anchored on two main runs a day, at 00 and 12 UTC, though ECMWF has expanded its higher-frequency products over time.

GFS: the American workhorse

The GFS is run by NOAA's National Centers for Environmental Prediction. It uses the FV3 (Finite Volume Cubed) dynamical core, runs at about 13 km resolution, and produces forecasts out to 16 days. Just as important, it updates four times a day, at 00, 06, 12 and 18 UTC, so it refreshes more often than the European headline run.

The GFS's other defining trait is openness. It has long been fully free and open: anyone, anywhere, can download the raw output at no cost. That is why the GFS quietly powers a huge share of the world's weather apps, websites and hobbyist forecasts.

Cost and openness

Historically this was the sharpest contrast between the two. The GFS was free; ECMWF's data sat largely behind a paywall and licensing terms. That has changed. ECMWF has moved through a phased open-data policy, starting an open subset of real-time forecasts in January 2022 and, from 1 October 2025, opening its entire real-time forecast catalogue for free at 25 km resolution in real time. The very highest-resolution 9 km products still carry licensing conditions for some professional uses, but the old picture of a completely closed European model no longer holds.

Track record: the Hurricane Sandy story

The most famous example of the two models diverging is Hurricane Sandy in October 2012. Days before landfall, the ECMWF consistently forecast Sandy taking a sharp northwest turn back into the US East Coast, while the GFS kept nudging the storm out to sea.

The ECMWF model was among the first to show the northwest turn at six and seven days out, correctly signalling a US landfall while the American guidance still favoured a track into the open Atlantic.

The European model was right, and that early warning helped emergency planners along the New Jersey and New York coasts. Later research in Geophysical Research Letters found the difference came down mainly to how each model handled a technical detail called cumulus parameterization, not resolution alone. It is a reminder that model skill is about the whole system, not just grid size.

Why forecasters watch both, and why neither always wins

Sandy made ECMWF famous, but it did not make it infallible. On any given day, either model can be closer to reality. The European model wins more verification scores on average over long records, yet the American model regularly beats it for specific storms, regions or timeframes, and its four-times-daily refresh can catch changes sooner.

That is exactly why experienced forecasters never rely on a single model. When ECMWF and GFS agree, confidence is high. When they split, that disagreement is itself useful information: it flags a genuinely uncertain situation where you should expect the forecast to shift.

Resolution: ECMWF around 9 km, GFS around 13 km.
Update frequency: GFS four times a day; ECMWF's headline run twice a day.
Cost: GFS always free and open; ECMWF now free at 25 km in real time, with premium high-resolution tiers.
Average accuracy: ECMWF usually leads global rankings, but not on every storm.

This is the whole reason a comparison site exists. Seeing the models side by side, rather than trusting one black-box app, tells you when the atmosphere is predictable and when it is not. You can compare them for your area on the compare US forecasts and compare UK forecasts pages.