From 8c6ce299da06f8ce503ede537f5a00eecac75f58 Mon Sep 17 00:00:00 2001
From: soutrikdas <valusoutrik@gmail.com>
Date: Thu, 22 Oct 2026 17:20:46 +0530
Subject: [PATCH 1/2] Start emitting deprecation warning for Dataset.to_array
 (GH11721)

Dataset.to_array is deprecated in favor of Dataset.to_dataarray
but no warnings were being emitted. Add a FutureWarning there.
Add a test to check if warning is being emitted.
---
 doc/whats-new.rst            | 5 +++++
 xarray/core/dataset.py       | 4 ++++
 xarray/tests/test_dataset.py | 7 +++++++
 3 files changed, 16 insertions(+)

diff --git a/doc/whats-new.rst b/doc/whats-new.rst
index 3abeff78a77..fa603976979 100644
--- a/doc/whats-new.rst
+++ b/doc/whats-new.rst
@@ -143,6 +143,11 @@ Deprecations
   :py:attr:`DataTree.lineage` warns once instead of twice (:issue:`11721`,
   :pull:`11724`).
   By `Daisy DAI <https://github.com/ShinoKana>`_.
+- :py:meth:`Dataset.to_array` is deprecated in favor of :py:meth:`Dataset.to_dataarray`
+  but it did not emit any warning previously, now it emits a ``FutureWarning``
+  (:issue:`11721`).
+  By `Soutrik Das <https://github.com/SoutrikDas>`_.
+
 
 
 Bug Fixes
diff --git a/xarray/core/dataset.py b/xarray/core/dataset.py
index 7976a8b5f62..ccec59b403d 100644
--- a/xarray/core/dataset.py
+++ b/xarray/core/dataset.py
@@ -7316,6 +7316,10 @@ def to_array(
         self, dim: Hashable = "variable", name: Hashable | None = None
     ) -> DataArray:
         """Convert this dataset into a DataArray (deprecated, use to_dataarray)."""
+        emit_user_level_warning(
+            "Dataset.to_array is deprecated, use Dataset.to_dataarray instead.",
+            FutureWarning,
+        )
         return self.to_dataarray(dim=dim, name=name)
 
     def _normalize_dim_order(
diff --git a/xarray/tests/test_dataset.py b/xarray/tests/test_dataset.py
index a0887c5b9cb..21a26e1e34e 100644
--- a/xarray/tests/test_dataset.py
+++ b/xarray/tests/test_dataset.py
@@ -3667,6 +3667,13 @@ def test_swap_dims(self) -> None:
         assert isinstance(actual.variables["x"], Variable)
         assert actual.xindexes["y"].equals(expected.xindexes["y"])
 
+    def test_to_array_deprecated(self) -> None:
+        ds = Dataset({"a": 1, "b": ("x", [1, 2, 3])}, coords={"c": 42})
+        expected = ds.to_dataarray("abc", name="foo")
+        with pytest.warns(FutureWarning, match=r"Dataset\.to_array is deprecated"):
+            actual = ds.to_array("abc", name="foo")
+        assert_identical(expected, actual)
+
     def test_expand_dims_error(self) -> None:
         original = Dataset(
             {

From d6c2f6200102f50426c403ba87d940dcd74925f5 Mon Sep 17 00:00:00 2001
From: soutrikdas <valusoutrik@gmail.com>
Date: Thu, 22 Oct 2026 17:29:11 +0530
Subject: [PATCH 2/2] Add PR Number to whats-new

---
 doc/whats-new.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/whats-new.rst b/doc/whats-new.rst
index fa603976979..a4d12d11227 100644
--- a/doc/whats-new.rst
+++ b/doc/whats-new.rst
@@ -145,7 +145,7 @@ Deprecations
   By `Daisy DAI <https://github.com/ShinoKana>`_.
 - :py:meth:`Dataset.to_array` is deprecated in favor of :py:meth:`Dataset.to_dataarray`
   but it did not emit any warning previously, now it emits a ``FutureWarning``
-  (:issue:`11721`).
+  (:issue:`11721`, :pull:`11788`).
   By `Soutrik Das <https://github.com/SoutrikDas>`_.