Is the National Blend of Models (NBM) a weather model?

Not in the usual sense. The NBM does not run its own physics simulation of the atmosphere. It is a statistical blend from NOAA's National Weather Service that combines many models, including global, regional and ensemble systems, into one calibrated, high-resolution forecast. Over the continental US it runs on a 2.5 km grid and serves as the official starting point for NWS public forecasts.

Are UKMO and ACCESS related?

Yes. Australia's ACCESS model is built on the UK Met Office's Unified Model, then adapted and tuned for Australian conditions by the Bureau of Meteorology. So the UK's UKMO and Australia's ACCESS share a common modelling heritage, even though they are run by different national services for different regions.

Why is Australia's ACCESS data limited on comparison sites?

The Bureau of Meteorology makes much of its gridded ACCESS output available to registered subscribers rather than as a fully free, open public download. That means real-time ACCESS coverage on comparison sites can be thinner than for the US, UK or Canadian models. We show what is available and say clearly when the feed is restricted.

Should I trust the national model over ECMWF or GFS?

Not automatically. National models are built for their own region and can be sharper on local detail like sea breezes, mountains and coastlines, but they do not always beat the global ECMWF or GFS. The most reliable read comes from comparing them side by side: agreement means high confidence, disagreement flags real uncertainty.

Guides›The national forecast models, explained: NBM, UKMO, GEM and ACCESS

The national forecast models, explained: NBM, UKMO, GEM and ACCESS

Beyond the global giants, each country runs its own official weather model tuned to its own skies. Here is what the USA, UK, Canada and Australia use, and who runs them.

Beyond the global giants

Global models like ECMWF and GFS cover the whole planet, but they are not the only forecasts that matter. Each country also runs its own official national system, developed and maintained by its government weather service and often tuned to the terrain, coastlines and weather patterns of that specific region. These are the models that sit behind the forecasts your national weather service issues.

checkweather.io shows four of them side by side: the USA's National Blend of Models, the UK Met Office model, Canada's GEM and Australia's ACCESS. Here is what each one actually is.

United States: the National Blend of Models (NBM)

The NBM, run by NOAA's National Weather Service, is a little different from the others on this list. It is not a single physics simulation. Instead it is a statistical blend that combines many models, including global, regional, deterministic and ensemble systems, into one calibrated, high-resolution forecast.

Over the continental US the NBM produces guidance on a 2.5 km grid, with other resolutions for Alaska, Hawaii, Puerto Rico, Guam and beyond. The blending is far more sophisticated than a simple average: it is calibrated to correct for known biases while keeping local detail. The NBM is the official starting point for the National Weather Service's public forecasts, which makes it one of the most consequential forecast products in the country. You can see it on the compare US forecasts page.

United Kingdom: the Met Office Unified Model (UKMO)

The UK's official model is the Met Office's Unified Model, usually shortened to UKMO or just UM. Its global deterministic configuration runs at roughly 10 km resolution and keeps its picture of the atmosphere anchored to reality using an advanced technique called hybrid 4D-Var data assimilation, which continuously folds in fresh observations.

The Unified Model is called unified because the same core code is used across timescales, from short-range weather forecasts right through to climate projections. It is the Met Office's flagship system and the engine behind official UK forecasts and warnings. See it on the compare UK forecasts page.

Canada: GEM (Environment and Climate Change Canada)

Canada's national model is GEM, the Global Environmental Multiscale model, developed and run by the Canadian Centre for Meteorological and Environmental Prediction within Environment and Climate Change Canada (ECCC).

GEM's global deterministic configuration runs at about 15 km resolution and couples the atmosphere to ocean and sea-ice components. A distinctive feature is its variable-resolution grid, which lets the same model run at coarser scales globally and much finer scales, down to 2.5 km, over Canada. GEM is also notably transparent: its source code is published openly by ECCC. It is the official Canadian system and appears on the compare Canadian forecasts page.

Australia: ACCESS (Bureau of Meteorology)

Australia's official model is ACCESS, the Australian Community Climate and Earth-System Simulator, run by the Bureau of Meteorology (BOM). ACCESS is built on the UK Met Office's Unified Model, adapted and tuned for Australian conditions, and it runs in several configurations from a global model down to high-resolution city-scale domains.

One honest caveat: Australia's open data feed for ACCESS is currently limited compared with the other services here. BOM makes gridded ACCESS output available largely to registered subscribers rather than as a fully free public download, so real-time coverage on comparison sites can be thinner than for the US, UK or Canadian models. We show what is available and are upfront when the feed is restricted. See the compare Australian forecasts page.

Why show the national models at all

If the global models already cover everywhere, why bother with national ones? Because national services build these systems specifically for their own region, often at higher resolution over land and with data assimilation tuned to their local observation networks. That can make them sharper for local detail: sea breezes, mountain effects, snow lines and coastal storms.

NBM (USA, NOAA/NWS): a calibrated blend of many models, 2.5 km over the continental US, feeds official NWS forecasts.
UKMO (UK, Met Office): the Unified Model, roughly 10 km global, the Met Office flagship.
GEM (Canada, ECCC): around 15 km global with a variable-resolution grid and open source code.
ACCESS (Australia, BOM): based on the UK Unified Model; official BOM system with a currently limited open feed.

None of these is guaranteed to beat the global models on a given day, and none is guaranteed to beat each other. Seeing the official national model next to ECMWF and GFS tells you when everyone agrees and when they do not, which is exactly the information a single weather app hides from you.