diff --git a/docs/en/api-guides/build-system.rst b/docs/en/api-guides/build-system.rst
index f5d7a6f8b5..d4fee5066f 100644
--- a/docs/en/api-guides/build-system.rst
+++ b/docs/en/api-guides/build-system.rst
@@ -113,8 +113,9 @@ Here is a list of some useful options:
 - ``-B <dir>`` allows overriding the build directory from the default ``build`` subdirectory of the project directory.
 - ``--ccache`` flag can be used to enable CCache_ when compiling source files, if the CCache_ tool is installed. This can dramatically reduce some build times.
 
-Note that some older versions of CCache may exhibit bugs on some platforms, so if files are not rebuilt as expected then try disabling ccache and build again. CCache can be enabled by default by setting the ``IDF_ENABLE_CCACHE`` environment variable to a non-zero value.
+Note that some older versions of CCache may exhibit bugs on some platforms, so if files are not rebuilt as expected then try disabling ccache and build again. CCache can be enabled by default by setting the ``IDF_CCACHE_ENABLE`` environment variable to a non-zero value.
 - ``-v`` flag causes both ``idf.py`` and the build system to produce verbose build output. This can be useful for debugging build problems.
+- ``--cmake-warn-uninitialized`` (or ``-w``) will cause CMake to print uninitialized variable warnings inside the project directory (not for directories not found inside the project directory). This only controls CMake variable warnings inside CMake itself, not other types of build warnings. This option can also be set permanently by setting the ``IDF_CMAKE_WARN_UNINITIALIZED`` environment variable to a non-zero value.
 
 Using CMake Directly
 --------------------
diff --git a/tools/idf_py_actions/core_ext.py b/tools/idf_py_actions/core_ext.py
index 182194785b..7ff2e522b2 100644
--- a/tools/idf_py_actions/core_ext.py
+++ b/tools/idf_py_actions/core_ext.py
@@ -210,8 +210,10 @@ def action_extensions(base_actions, project_path):
                 "default": None,
             },
             {
-                "names": ["-n", "--no-warnings"],
-                "help": "Disable Cmake warnings.",
+                "names": ["-w/-n", "--cmake-warn-uninitialized/--no-warnings"],
+                "help": ("Enable CMake uninitialized variable warnings for CMake files inside the project directory. "
+                         "(--no-warnings is now the default, and doesn't need to be specified.)"),
+                "envvar": "IDF_CMAKE_WARN_UNINITIALIZED",
                 "is_flag": True,
                 "default": False,
             },
diff --git a/tools/idf_py_actions/tools.py b/tools/idf_py_actions/tools.py
index 788bcca5e3..356c5bc374 100644
--- a/tools/idf_py_actions/tools.py
+++ b/tools/idf_py_actions/tools.py
@@ -199,7 +199,7 @@ def ensure_build_directory(args, prog_name, always_run_cmake=False):
                 "-DPYTHON_DEPS_CHECKED=1",
                 "-DESP_PLATFORM=1",
             ]
-            if not args.no_warnings:
+            if args.cmake_warn_uninitialized:
                 cmake_args += ["--warn-uninitialized"]
 
             if args.define_cache_entry: