From 104d1ef0c9748daf37cb141be984945e0cb0fb60 Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Mon, 3 Feb 2020 07:36:35 +0000
Subject: [PATCH] Backport PR #31207: BUG: no longer raise user warning when
 plotting tz aware time series

---
 doc/source/whatsnew/v1.0.1.rst             | 2 +-
 pandas/plotting/_matplotlib/timeseries.py  | 2 +-
 pandas/tests/plotting/test_datetimelike.py | 5 +++--
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/doc/source/whatsnew/v1.0.1.rst b/doc/source/whatsnew/v1.0.1.rst
index 71a67e10ca38c..684dcb1cbf002 100644
--- a/doc/source/whatsnew/v1.0.1.rst
+++ b/doc/source/whatsnew/v1.0.1.rst
@@ -95,7 +95,7 @@ I/O
 Plotting
 ^^^^^^^^
 
--
+- Plotting tz-aware timeseries no longer gives UserWarning (:issue:`31205`)
 -
 
 Groupby/resample/rolling
diff --git a/pandas/plotting/_matplotlib/timeseries.py b/pandas/plotting/_matplotlib/timeseries.py
index dd048114142f3..3abce690cbe6b 100644
--- a/pandas/plotting/_matplotlib/timeseries.py
+++ b/pandas/plotting/_matplotlib/timeseries.py
@@ -251,7 +251,7 @@ def _maybe_convert_index(ax, data):
         freq = frequencies.get_period_alias(freq)
 
         if isinstance(data.index, ABCDatetimeIndex):
-            data = data.to_period(freq=freq)
+            data = data.tz_localize(None).to_period(freq=freq)
         elif isinstance(data.index, ABCPeriodIndex):
             data.index = data.index.asfreq(freq=freq)
     return data
diff --git a/pandas/tests/plotting/test_datetimelike.py b/pandas/tests/plotting/test_datetimelike.py
index 8f855fd0c6cff..10d7efd22971b 100644
--- a/pandas/tests/plotting/test_datetimelike.py
+++ b/pandas/tests/plotting/test_datetimelike.py
@@ -45,11 +45,12 @@ def teardown_method(self, method):
 
     @pytest.mark.slow
     def test_ts_plot_with_tz(self, tz_aware_fixture):
-        # GH2877, GH17173
+        # GH2877, GH17173, GH31205
         tz = tz_aware_fixture
         index = date_range("1/1/2011", periods=2, freq="H", tz=tz)
         ts = Series([188.5, 328.25], index=index)
-        _check_plot_works(ts.plot)
+        with tm.assert_produces_warning(None):
+            _check_plot_works(ts.plot)
 
     def test_fontsize_set_correctly(self):
         # For issue #8765