diff -r 7ae156f07a90 Lib/tempfile.py
--- a/Lib/tempfile.py	Sun Feb 15 00:45:57 2015 +0200
+++ b/Lib/tempfile.py	Sun Feb 15 11:02:28 2015 +0200
@@ -166,6 +166,13 @@ def _get_default_tempdir():
                 return dir
             except FileExistsError:
                 pass
+            except PermissionError:
+                # This exception is thrown when a directory with the chosen name
+                # already exists on windows.
+                if _os.name == 'nt' and _os.access(dir, _os.W_OK):
+                    continue
+                else:
+                    break   # no point trying more names in this directory
             except OSError:
                 break   # no point trying more names in this directory
     raise FileNotFoundError(_errno.ENOENT,
@@ -204,7 +211,7 @@ def _mkstemp_inner(dir, pre, suf, flags)
         except PermissionError:
             # This exception is thrown when a directory with the chosen name
             # already exists on windows.
-            if _os.name == 'nt':
+            if _os.name == 'nt' and _os.access(dir, _os.W_OK):
                 continue
             else:
                 raise
@@ -296,6 +303,13 @@ def mkdtemp(suffix="", prefix=template, 
             return file
         except FileExistsError:
             continue    # try again
+        except PermissionError:
+            # This exception is thrown when a directory with the chosen name
+            # already exists on windows.
+            if _os.name == 'nt' and _os.access(dir, _os.W_OK):
+                continue
+            else:
+                raise
 
     raise FileExistsError(_errno.EEXIST,
                           "No usable temporary directory name found")
diff -r 7ae156f07a90 Lib/test/test_tempfile.py
--- a/Lib/test/test_tempfile.py	Sun Feb 15 00:45:57 2015 +0200
+++ b/Lib/test/test_tempfile.py	Sun Feb 15 11:02:28 2015 +0200
@@ -274,7 +274,36 @@ def _mock_candidate_names(*names):
                              lambda: iter(names))
 
 
-class TestMkstempInner(BaseTestCase):
+class TestBadTempdir:
+
+    def test_read_only_directory(self):
+        with _inside_empty_temp_dir():
+            mode = os.stat(tempfile.tempdir).st_mode
+            mode &= ~(stat.S_IWUSR | stat.S_IWGRP | stat.S_IWOTH)
+            os.chmod(tempfile.tempdir, mode)
+            if os.access(tempfile.tempdir, os.W_OK):
+                self.skipTest("can't set the directory read-only")
+            with self.assertRaises(PermissionError):
+                self.make_temp()
+            self.assertEqual(os.listdir(tempfile.tempdir), [])
+
+    def test_nonexisting_directory(self):
+        with _inside_empty_temp_dir():
+            tempdir = os.path.join(tempfile.tempdir, 'nonexistent')
+            with support.swap_attr(tempfile, 'tempdir', tempdir):
+                with self.assertRaises(FileNotFoundError):
+                    self.make_temp()
+
+    def test_non_directory(self):
+        with _inside_empty_temp_dir():
+            tempdir = os.path.join(tempfile.tempdir, 'file')
+            open(tempdir, 'wb').close()
+            with support.swap_attr(tempfile, 'tempdir', tempdir):
+                with self.assertRaises(NotADirectoryError):
+                    self.make_temp()
+
+
+class TestMkstempInner(TestBadTempdir, BaseTestCase):
     """Test the internal function _mkstemp_inner."""
 
     class mkstemped:
@@ -395,6 +424,8 @@ class TestMkstempInner(BaseTestCase):
                                        '',
                                        tempfile._bin_openflags)
 
+    make_temp = default_mkstemp_inner
+
     def test_collision_with_existing_file(self):
         # _mkstemp_inner tries another name when a file with
         # the chosen name already exists
@@ -528,9 +559,12 @@ class TestMkstemp(BaseTestCase):
             os.rmdir(dir)
 
 
-class TestMkdtemp(BaseTestCase):
+class TestMkdtemp(TestBadTempdir, BaseTestCase):
     """Test mkdtemp()."""
 
+    def make_temp(self):
+        return tempfile.mkdtemp()
+
     def do_create(self, dir=None, pre="", suf=""):
         if dir is None:
             dir = tempfile.gettempdir()