diff --git src/wp-includes/script-loader.php src/wp-includes/script-loader.php
index a97bfe1..0def108 100644
--- src/wp-includes/script-loader.php
+++ src/wp-includes/script-loader.php
@@ -233,6 +233,32 @@ function wp_default_scripts( &$scripts ) {
 		'manyResults' => __( '%d results found. Use up and down arrow keys to navigate.' ),
 	) );
 
+	// Localized jQuery UI datepicker
+	global $wp_locale;
+
+	$datepicker_args = array(
+		'jqueryUiDatepicker' => array(
+			'closeText'       => esc_js( __( 'Close' ) ),
+			'currentText'     => esc_js( __( 'Today' ) ),
+			'monthNames'      => array_values( $wp_locale->month ),
+			'monthNamesShort' => array_values( $wp_locale->month_abbrev ),
+			'monthStatus'     => esc_js( __( 'Show a different month' ) ),
+			'nextText'        => esc_js( __( 'Next' ) ),
+			'prevText'        => esc_js( __( 'Previous' ) ),
+			'dayNames'        => array_values( $wp_locale->weekday ),
+			'dayNamesShort'   => array_values( $wp_locale->weekday_abbrev ),
+			'dayNamesMin'     => array_values( $wp_locale->weekday_initial ),
+			'dateFormat'      => esc_js( get_option( 'date_format' ) ),
+			'firstDay'        => absint( get_option( 'start_of_week' ) ),
+			'isRTL'           => $wp_locale->is_rtl(),
+		),
+	);
+
+	$scripts->localize( 'jquery-ui-datepicker', 'wpl10n', $datepicker_args );
+
+	$localized_datepicker = 'jQuery(document).ready(function(jQuery) { jQuery.datepicker.setDefaults(wpl10n.jqueryUiDatepicker); });';
+	$scripts->add_inline_script( 'jquery-ui-datepicker', $localized_datepicker );
+
 	// deprecated, not used in core, most functionality is included in jQuery 1.3
 	$scripts->add( 'jquery-form', "/wp-includes/js/jquery/jquery.form$suffix.js", array('jquery'), '3.37.0', 1 );