diff --git a/conftest.py b/conftest.py
index d61f5277b2ba..9f2dd5516e73 100644
--- a/conftest.py
+++ b/conftest.py
@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import pytest
+import numpy as np
 
 
 def pytest_addoption(parser):
@@ -25,6 +26,12 @@ def pytest_addoption(parser):
     parser.addoption(
         "--enable-slow-tests", action="store_true", default=False, help="run slow tests"
     )
+    parser.addoption(
+        "--warn-numpy-data-promotion",
+        action="store_true",
+        default=False,
+        help="enable NumPy 2 data type promotion warnings"
+    )
 
 
 def pytest_collection_modifyitems(config, items):
@@ -48,6 +55,11 @@ def pytest_collection_modifyitems(config, items):
         del skip_marks["slow"]  # pragma: no cover
     skip_keywords = frozenset(skip_marks.keys())
 
+    # If requested, globally enable verbose NumPy 2 warnings about data type
+    # promotion. See https://numpy.org/doc/2.0/numpy_2_0_migration_guide.html.
+    if config.option.warn_numpy_data_promotion:
+        np._set_promotion_state("weak_and_warn")
+
     for item in items:
         for k in skip_keywords.intersection(item.keywords):
             item.add_marker(skip_marks[k])