# \[Data Announcement\] Revamped chunking for ERA5 Zarr datasets on Earth Data Hub

**URL:** https://discourse.pangeo.io/t/data-announcement-revamped-chunking-for-era5-zarr-datasets-on-earth-data-hub/5776
**Category:** News & Announcements
**Tags:** zarr
**Created:** [July 6, 2026, 3:34pm UTC](https://discourse.pangeo.io/t/data-announcement-revamped-chunking-for-era5-zarr-datasets-on-earth-data-hub/5776 "2026-07-06T15:34:28Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![Nicola\_Masotti](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.pangeo.io/nicola_masotti/32/3792_2.png) [@Nicola\_Masotti](https://discourse.pangeo.io/u/Nicola_Masotti)
#### Post date: [July 6, 2026, 3:34pm UTC](https://discourse.pangeo.io/t/data-announcement-revamped-chunking-for-era5-zarr-datasets-on-earth-data-hub/5776/1 "2026-07-06T15:34:28Z")

</div>

**[Data Announcement] Revamped chunking for ERA5 Zarr datasets on Earth Data Hub**

The [Earth Data Hub](https://earthdatahub.destine.eu/) just migrated all its [ERA5 Zarr datasets](https://earthdatahub.destine.eu/collections/era5) to Zarr v3 and revamped their chunking along the way!

Here’s what’s changed:

🔹 Reduced chunk size: while each ERA5 dataset on Earth Data Hub retains its own tailored chunking, we have generally reduced the chunk size across the collection.

🔹 Better Regional Access: this new chunking schema drastically improves data access time for users dealing with regional maps and transient events (e.g., floods, heatwaves, etc.).

🔹 Balanced Performance: we carefully fine-tuned the chunk sizes to ensure you get faster regional slices without the overhead of making too many requests, i.e. long time series requests (30+ years) will not slow down.

🗓 Quick Reminder: the data within our ERA5-Zarr mirror is always available up to the last closed month and continues to be updated on a reliable monthly basis.

**Try it out:**

```auto
import xarray as xr

EDH_API_KEY = "your_EDH_api_key"
# can be found at: https://earthdatahub.destine.eu/account-settings

xr.open_dataset(
    f"https://edh:{EDH_API_KEY}@api.earthdatahub.destine.eu/era5/era5-single-levels-atmosphere-v0.zarr",
    chunks={},
    engine="zarr",
)

```