diff --git a/.readthedocs.yml b/.readthedocs.yml
index af1a8f6303..d82bd513ca 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -1,9 +1,9 @@
 version: 2
 
 build:
-  os: ubuntu-20.04
+  os: "ubuntu-22.04"
   tools:
-    python: mambaforge-4.10
+    python: "mambaforge-22.9"
   jobs:
     post_checkout:
       # The SciTools/iris repository is shallow i.e., has a .git/shallow,
diff --git a/docs/src/whatsnew/latest.rst b/docs/src/whatsnew/latest.rst
index dfc1019683..41f765bfe1 100644
--- a/docs/src/whatsnew/latest.rst
+++ b/docs/src/whatsnew/latest.rst
@@ -120,6 +120,9 @@ This document explains the changes made to Iris for this release
 #. `@bjlittle`_ enforced the minimum pin of ``numpy>1.22`` in accordance with the `NEP29 Drop Schedule`_.
    (:pull:`5668`)
 
+#. `@bjlittle`_ updated ``ubuntu`` and ``mambaforge`` to the latest versions for ``readthedocs``
+   (:pull:`5702`)
+
 
 📚 Documentation
 ================