diff --git a/core/modules/datetime/src/Plugin/Field/FieldFormatter/DateTimeCustomFormatter.php b/core/modules/datetime/src/Plugin/Field/FieldFormatter/DateTimeCustomFormatter.php
index 984423d..ca40045 100644
--- a/core/modules/datetime/src/Plugin/Field/FieldFormatter/DateTimeCustomFormatter.php
+++ b/core/modules/datetime/src/Plugin/Field/FieldFormatter/DateTimeCustomFormatter.php
@@ -54,7 +54,7 @@ public function viewElements(FieldItemListInterface $items, $langcode) {
    */
   protected function formatDate($date) {
     $format = $this->getSetting('date_format');
-    $timezone = $this->getSetting('timezone_override');
+    $timezone = $this->getSetting('timezone_override') ?: $date->getTimezone()->getName();
     return $this->dateFormatter->format($date->getTimestamp(), 'custom', $format, $timezone != '' ? $timezone : NULL);
   }
 
diff --git a/core/modules/datetime/src/Plugin/Field/FieldFormatter/DateTimePlainFormatter.php b/core/modules/datetime/src/Plugin/Field/FieldFormatter/DateTimePlainFormatter.php
index 7f0dee2..875d1de 100644
--- a/core/modules/datetime/src/Plugin/Field/FieldFormatter/DateTimePlainFormatter.php
+++ b/core/modules/datetime/src/Plugin/Field/FieldFormatter/DateTimePlainFormatter.php
@@ -41,7 +41,7 @@ public function viewElements(FieldItemListInterface $items, $langcode) {
    */
   protected function formatDate($date) {
     $format = $this->getFieldSetting('datetime_type') == DateTimeItem::DATETIME_TYPE_DATE ? DATETIME_DATE_STORAGE_FORMAT : DATETIME_DATETIME_STORAGE_FORMAT;
-    $timezone = $this->getSetting('timezone_override');
+    $timezone = $this->getSetting('timezone_override') ?: $date->getTimezone()->getName();
     return $this->dateFormatter->format($date->getTimestamp(), 'custom', $format, $timezone != '' ? $timezone : NULL);
   }
 
diff --git a/core/modules/datetime/tests/src/Functional/DateTimeFieldTest.php b/core/modules/datetime/tests/src/Functional/DateTimeFieldTest.php
index 3df2582..8758f69 100644
--- a/core/modules/datetime/tests/src/Functional/DateTimeFieldTest.php
+++ b/core/modules/datetime/tests/src/Functional/DateTimeFieldTest.php
@@ -133,13 +133,14 @@ public function testDateField() {
       $output = $this->renderTestEntity($id);
       $this->assertContains($expected, $output, SafeMarkup::format('Formatted date field using plain format displayed as %expected.', ['%expected' => $expected]));
 
-      // Verify that the 'datetime_custom' formatter works.
+      // Verify that the 'datetime_custom' formatter works. Make sure the date
+      // is in UTC, which is the proper time zone handling for date only fields.
       $this->displayOptions['type'] = 'datetime_custom';
-      $this->displayOptions['settings'] = ['date_format' => 'm/d/Y'] + $this->defaultSettings;
+      $this->displayOptions['settings'] = ['date_format' => 'm/d/Y e'] + $this->defaultSettings;
       entity_get_display($this->field->getTargetEntityTypeId(), $this->field->getTargetBundle(), 'full')
         ->setComponent($field_name, $this->displayOptions)
         ->save();
-      $expected = $date->format($this->displayOptions['settings']['date_format']);
+      $expected = $date->format('m/d/Y \U\T\C');
       $output = $this->renderTestEntity($id);
       $this->assertContains($expected, $output, SafeMarkup::format('Formatted date field using datetime_custom format displayed as %expected.', ['%expected' => $expected]));
 
diff --git a/core/modules/datetime_range/tests/src/Functional/DateRangeFieldTest.php b/core/modules/datetime_range/tests/src/Functional/DateRangeFieldTest.php
index e7f0fbb..81f5d85 100644
--- a/core/modules/datetime_range/tests/src/Functional/DateRangeFieldTest.php
+++ b/core/modules/datetime_range/tests/src/Functional/DateRangeFieldTest.php
@@ -161,13 +161,15 @@ public function testDateRangeField() {
       $output = $this->renderTestEntity($id);
       $this->assertContains($expected, $output, new FormattableMarkup('Formatted date field using plain format displayed as %expected.', ['%expected' => $expected]));
 
-      // Verify that the custom formatter works.
+      // Verify that the 'datetime_custom' formatter works. Make sure the dates
+      // are in UTC, which is the proper time zone handling for date only
+      // fields.
       $this->displayOptions['type'] = 'daterange_custom';
-      $this->displayOptions['settings'] = ['date_format' => 'm/d/Y'] + $this->defaultSettings;
+      $this->displayOptions['settings'] = ['date_format' => 'm/d/Y e'] + $this->defaultSettings;
       entity_get_display($this->field->getTargetEntityTypeId(), $this->field->getTargetBundle(), 'full')
         ->setComponent($field_name, $this->displayOptions)
         ->save();
-      $expected = $start_date->format($this->displayOptions['settings']['date_format']) . ' - ' . $end_date->format($this->displayOptions['settings']['date_format']);
+      $expected = $start_date->format('m/d/Y \U\T\C') . ' - ' . $end_date->format('m/d/Y \U\T\C');
       $output = $this->renderTestEntity($id);
       $this->assertContains($expected, $output, new FormattableMarkup('Formatted date field using daterange_custom format displayed as %expected.', ['%expected' => $expected]));