diff --git a/docs/source/conf.py b/docs/source/conf.py
index 2cba9363..54908e49 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -7,12 +7,9 @@
 # -- Import and path setup ---------------------------------------------------
 
 import datetime
-import json
 import os
 import sys
 
-import yaml
-
 on_rtd = os.environ.get("READTHEDOCS") == "True"
 
 if on_rtd:
@@ -30,6 +27,16 @@
 else:
     source_branch = "main"
 
+# Branch for upstream earthkit repo (used for fetching earthkit-packages.yml)
+# Tags will use main
+if rtd_version_type in ("tag"):
+    ek_branch = "main"
+# Pull requests and unknmown versions will use develop
+# Not sure how you get unknown, but its a valid value of rtd_version_type
+elif rtd_version_type in ("external", "unknown"):
+    ek_branch = "develop"
+else:
+    ek_branch = rtd_version
 
 sys.path.insert(0, os.path.abspath("../../src"))
 sys.path.insert(0, os.path.abspath("./"))
@@ -235,21 +242,9 @@
 }
 
 
-def _write_earthkit_packages_js(app):
-    """Read earthkit-packages.yml and write a JS data file into the output _static dir."""
-    config_path = os.path.join(os.path.dirname(__file__), "earthkit-packages.yml")
-    with open(config_path, encoding="utf-8") as fh:
-        config = yaml.safe_load(fh)
-    packages = config.get("packages", [])
-    static_dir = os.path.join(app.outdir, "_static")
-    os.makedirs(static_dir, exist_ok=True)
-    js_path = os.path.join(static_dir, "earthkit-packages.js")
-    with open(js_path, "w", encoding="utf-8") as fh:
-        fh.write(f"window.earthkitPackages = {json.dumps(packages)};\n")
-
-
 def setup(app):
+    from earthkit_packages import _write_earthkit_packages_js
     from skip_api_rules import _skip_api_items
 
-    app.connect("builder-inited", _write_earthkit_packages_js)
+    app.connect("builder-inited", lambda app: _write_earthkit_packages_js(app, ek_branch))
     app.connect("autoapi-skip-member", _skip_api_items)
diff --git a/docs/source/earthkit_packages.py b/docs/source/earthkit_packages.py
new file mode 100644
index 00000000..b5952b86
--- /dev/null
+++ b/docs/source/earthkit_packages.py
@@ -0,0 +1,43 @@
+# (C) Copyright 2021 ECMWF.
+#
+# This software is licensed under the terms of the Apache Licence Version 2.0
+# which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
+# In applying this licence, ECMWF does not waive the privileges and immunities
+# granted to it by virtue of its status as an intergovernmental organisation
+# nor does it submit to any jurisdiction.
+#
+
+import json
+import os
+import urllib.request
+
+import yaml
+
+
+def _write_earthkit_packages_js(app, ek_branch):
+    """Fetch earthkit-packages.yml from remote and write a JS data file into the output _static dir.
+
+    Falls back to the local copy if the remote fetch fails.
+    """
+    urls = (
+        f"https://raw.githubusercontent.com/ecmwf/earthkit/refs/heads/{ek_branch}/docs/earthkit-packages.yml",
+        "https://raw.githubusercontent.com/ecmwf/earthkit/refs/heads/main/docs/earthkit-packages.yml",
+        "https://raw.githubusercontent.com/ecmwf/earthkit/refs/heads/develop/docs/earthkit-packages.yml",
+    )
+
+    for url in urls:
+        try:
+            with urllib.request.urlopen(url, timeout=10) as response:
+                config = yaml.safe_load(response.read())
+                break
+        except Exception:
+            continue
+    else:
+        raise RuntimeError("Failed to fetch earthkit-packages.yml from remote URLs.")
+
+    packages = config.get("packages", [])
+    static_dir = os.path.join(app.outdir, "_static")
+    os.makedirs(static_dir, exist_ok=True)
+    js_path = os.path.join(static_dir, "earthkit-packages.js")
+    with open(js_path, "w", encoding="utf-8") as fh:
+        fh.write(f"window.earthkitPackages = {json.dumps(packages)};\n")