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Created by
Emma Pidduck, last updated yesterday at 9:26 am
2 minute read
From 20 October 2026, ECMWF open data is also available at 0.1°, alongside the existing 0.25°. Both come from the same high-resolution forecast (about 9 km); 0.1° and 0.25° are the distributed grid spacings. This page covers what is different about the 0.1° tier.
The 0.1° (high-resolution) data is published about 2 hours later than the 0.25° data. The 0.25° fields arrive at the end of the normal dissemination schedule; the finer 0.1° surface and pressure-level files follow roughly 2 hours afterwards, each with their own WIS2 notification. If your workflow expects both resolutions together, plan for this gap — the 0.1° data is not late, it is scheduled later.
How 0.1° differs from 0.25°
| Property | 0.25° (existing) | 0.1° (new) |
|---|---|---|
| Horizontal grid spacing | 0.25° | 0.1° — 2.5× finer |
| Grid points, same area | Baseline | 6.25× more points |
| Underlying forecast | ECMWF high-resolution (≈ 9 km) | Same forecast, finer grid |
| Parameters | The core open-data set | Core set plus extra fields for Forecast in a Box and for initialising limited area models |
| File structure | Surface and pressure-level fields combined | Surface and pressure-level fields supplied separately (see below) |
| When it is available | End of the dissemination schedule | About 2 hours after the dissemination schedule — see the warning above |
| WIS2 notifications | Yes | Yes — issued separately, because it arrives later |
| Encoding | Per-parameter bits-per-value | Per-parameter bits-per-value — see Bits per value |
Surface and pressure-level split
The 0.1° data is delivered as two separate files per run — one for surface fields (-sfc), one for pressure-level fields (-pl) — rather than one combined file. This lets users in low-bandwidth regions take only what they need (for example, surface fields alone) without downloading the much larger pressure-level set.
The 0.25° data stays combined: its bits-per-value reduction has already brought the volume down far enough that a split is not needed.
Additional parameters
The 0.1° tier carries extra fields beyond the 0.25° core set, to support:
- Forecast in a Box — running ECMWF's packaged forecast workflow locally.
- Limited area model initialisation — providing the model-level and pressure-level fields needed to drive a regional model from ECMWF boundary conditions.
These are largely upper-air / multi-level fields (temperature, wind components, humidity, geopotential and related dynamical fields). Many of these are the precision-sensitive fields held at a higher bits-per-value — see Bits per value.