diff --git a/environment.yml b/environment.yml
index ab1acac982..659cf4918d 100644
--- a/environment.yml
+++ b/environment.yml
@@ -21,7 +21,7 @@ dependencies:
   - humanfriendly
   - intake-esgf >=2025.10.22
   - intake-esm
-  - iris >=3.12.2  # https://github.com/SciTools/iris/issues/6417
+  - iris >=3.12.2,<3.14.1 # https://github.com/SciTools/iris/issues/6417, https://github.com/ESMValGroup/ESMValCore/issues/2921
   - iris-esmf-regrid >=0.11.0
   - iris-grib >=0.20.0  # github.com/ESMValGroup/ESMValCore/issues/2535
   - isodate >=0.7.0  # incompatible with very old 0.6.1
diff --git a/pyproject.toml b/pyproject.toml
index 9c7387422e..25487ece9f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -64,7 +64,7 @@ dependencies = [
     "requests",
     "rich",
     "scipy>=1.6",
-    "scitools-iris>=3.12.2",  # github.com/SciTools/iris/issues/6417
+    "scitools-iris>=3.12.2,<3.14.1",  # github.com/SciTools/iris/issues/6417, https://github.com/ESMValGroup/ESMValCore/issues/2921
     "shapely>=2.0.0",
     "stratify>=0.3",
     "xarray",