diff -u b/core/lib/Drupal/Core/Datetime/DateHelper.php b/core/lib/Drupal/Core/Datetime/DateHelper.php
--- b/core/lib/Drupal/Core/Datetime/DateHelper.php
+++ b/core/lib/Drupal/Core/Datetime/DateHelper.php
@@ -453,7 +453,7 @@
    *   The number of days in the month.
    */
   public static function daysInMonth($date = NULL) {
-    if (isset($date)) {
+    if (isset($date) && !empty($date)) {
       if (!$date instanceof DrupalDateTime) {
         $date = new DrupalDateTime($date);
       }
@@ -475,7 +475,7 @@
    *   The number of days in the year.
    */
   public static function daysInYear($date = NULL) {
-    if (isset($date)) {
+    if (isset($date) && !empty($date)) {
       if (!$date instanceof DrupalDateTime) {
         $date = new DrupalDateTime($date);
       }
@@ -502,7 +502,7 @@
    *   The number of the day in the week.
    */
   public static function dayOfWeek($date = NULL) {
-    if (isset($date)) {
+    if (isset($date) && !empty($date)) {
       if (!$date instanceof DrupalDateTime) {
         $date = new DrupalDateTime($date);
       }
@@ -527,7 +527,7 @@
    *   The name of the day in the week for that date.
    */
   public static function dayOfWeekName($date = NULL, $abbr = TRUE) {
-    if (isset($date)) {
+    if (isset($date) && !empty($date)) {
       if (!$date instanceof DrupalDateTime) {
         $date = new DrupalDateTime($date);
       }
diff -u b/core/tests/Drupal/Tests/Core/Datetime/DateHelperTest.php b/core/tests/Drupal/Tests/Core/Datetime/DateHelperTest.php
--- b/core/tests/Drupal/Tests/Core/Datetime/DateHelperTest.php
+++ b/core/tests/Drupal/Tests/Core/Datetime/DateHelperTest.php
@@ -165,6 +165,10 @@
   public function testDaysInMonth() {
     // Pass nothing and expect to get NULL.
     $this->assertNull(DateHelper::daysInMonth());
+    $this->assertNull(DateHelper::daysInMonth(FALSE));
+    $this->assertNull(DateHelper::daysInMonth(0));
+    $this->assertNull(DateHelper::daysInMonth('0'));
+    $this->assertNull(DateHelper::daysInMonth(''));
 
     // December 31st 2022 is a Saturday.
     $value = '2022-12-31 00:00:00';
@@ -183,6 +187,10 @@
   public function testDaysInYear() {
     // Pass nothing and expect to get NULL.
     $this->assertNull(DateHelper::daysInYear());
+    $this->assertNull(DateHelper::daysInYear(FALSE));
+    $this->assertNull(DateHelper::daysInYear(0));
+    $this->assertNull(DateHelper::daysInYear('0'));
+    $this->assertNull(DateHelper::daysInYear(''));
 
     // December 31st 2022 is a Saturday.
     $value = '2022-12-31 00:00:00';
@@ -201,6 +209,10 @@
   public function testDayOfWeek() {
     // Pass nothing and expect to get NULL.
     $this->assertNull(DateHelper::dayOfWeek());
+    $this->assertNull(DateHelper::dayOfWeek(FALSE));
+    $this->assertNull(DateHelper::dayOfWeek(0));
+    $this->assertNull(DateHelper::dayOfWeek('0'));
+    $this->assertNull(DateHelper::dayOfWeek(''));
 
     // December 31st 2022 is a Saturday.
     $value = '2022-12-31 00:00:00';
@@ -219,6 +231,10 @@
   public function testDayOfWeekName() {
     // Pass nothing and expect to get NULL.
     $this->assertNull(DateHelper::dayOfWeekName());
+    $this->assertNull(DateHelper::dayOfWeekName(FALSE));
+    $this->assertNull(DateHelper::dayOfWeekName(0));
+    $this->assertNull(DateHelper::dayOfWeekName('0'));
+    $this->assertNull(DateHelper::dayOfWeekName(''));
 
     // December 31st 2022 is a Saturday.
     $value = '2022-12-31 00:00:00';